Jesus was 12 years old during the Passover in AD 7. Joseph and Mary lost track of Jesus for about a day’s journey. When Joseph and Mary sorrowfully searched for Jesus, they found Jesus in the Temple. Jesus replied to Joseph and Mary in Luke 2:49. that "I must be about my Father’s business?"

The number 12 is identified with fullness. The work of Christ is to finish the harvest of souls. There are 1995 years from 7 AD to 2012 AD. The factors of 1995 is 3 (purposed by God), 5 (judgment/salvation), 7 (Sabbath of Harvest), 19 (identified with length of great tribulation)

The number 12 identified with fullness:
 

12 Apostles
 

Luke 22:14 And when the hour was come, he sat down, and the twelve apostles with him

12 Tribes of Israel

Exodus 39:14 And the stones were according to the names of the children of Israel, twelve, according to their names, like the engravings of a signet, every one with his name, according to the twelve tribes

Disciples gather the fragments of five barley loaves and filled twelve baskets:

John 6:13 Therefore they gathered them together, and filled twelve baskets with the fragments of the five barley loaves, which remained over and above unto them that had eaten.

Jesus was 12 during the passover season in 7 AD.

Luke 2:41 ¶ Now his parents went to Jerusalem every year at the feast of the passover.
Luke 2:42 And when he was twelve years old, they went up to Jerusalem after the custom of the feast.
Luke 2:43 And when they had fulfilled the days, as they returned, the child Jesus tarried behind in Jerusalem; and Joseph and his mother knew not of it.

The passover season is identified with beginning of the harvest season:

John 13:1 ¶ Now before the feast of the passover, when Jesus knew that his hour was come that he should depart out of this world unto the Father, having loved his own which were in the world, he loved them unto the end.

When Joseph and Mary sorrowfully searched for Jesus, they found Jesus in the Temple. Jesus s replied to Joseph and Mary in Luke 2:49. that "I must be about my Father’s business? The father business is to complete the harvest of souls:

John 6:37 All that the Father giveth me shall come to me; and him that cometh to me I will in no wise cast out.
John 6:38 For I came down from heaven, not to do mine own will, but the will of him that sent me.
John 6:39 And this is the Father’s will which hath sent me, that of all which he hath given me I should lose nothing, but should raise it up again at the last day.
John 6:40 And this is the will of him that sent me, that every one which seeth the Son, and believeth on him, may have everlasting life: and I will raise him up at the last day.

Matthew 13:37 He answered and said unto them, He that soweth the good seed is the Son of man;
Matthew 13:38 The field is the world; the good seed are the children of the kingdom; but the tares are the children of the wicked one;
Matthew 13:39 The enemy that sowed them is the devil; the harvest is the end of the world; and the reapers are the angels.
Matthew 13:40 As therefore the tares are gathered and burned in the fire; so shall it be in the end of this world.
Matthew 13:41 The Son of man shall send forth his angels, and they shall gather out of his kingdom all things that offend, and them which do iniquity;
Matthew 13:42 And shall cast them into a furnace of fire: there shall be wailing and gnashing of teeth.

Birth of Christ October 1, Day of Atonement (Gregorian) 7 BC - Abstract from Time has an End - Harold Camping /Family Radio pg. 314

pg. 314

...Assuming it took about two weeks to arrive in Elisabeth's house, it meant that Mary was about three and a half months pregnant when she left Elisabeth at the time John was born. As we learned earlier, the birth of John was about April 15, Thus, it appears Mary would have left Elisabeth. Therefore, Jesus would have been born about five and a half months later than April 15th or about October 1.

In any case, we know that the information concerning such things as the course of Abia, the sixth month of Elizabeth 's pregnancy, and the three-month visit of Mary with Elizabeth have been carefully placed in the Bible for a purpose. The purpose focuses on the date of Jesus' Birth. For certain it means that Jesus would have been born very close to October 1 in the year 7 B.C.

When we calculate the date of the day of atonement in 7 B.C. , we discover it was October 1, a date that appears to fit perfectly with our present conclusion that Jesus was born about October 1...

Used freeware Intercal by Denis A Elliot

Tidbit regarding October 1 : Note the accession of the Lord Jesus Christ to Heaven on May 11, 33 AD to October 1, 2012 AD (the Feast of Ingathering) there is a total of 722,959 days (Gregorian Vernal Equinox Based). The factors for the number 722,959 are 17 (Heaven), 23 (Judgment), 43 X 43 (Judgment/Salvation)

There are 1995 years from 7 AD to 2012 AD. The factors of 1995 is 3 (purposed by God), 5 (judgment/salvation), 7 (Sabbath of Harvest), 19 (identified with length of great tribulation)

The number 3 identified with purpose:

Deuteronomy 19:15 One witness shall not rise up against a man for any iniquity, or for any sin, in any sin that he sinneth: at the mouth of two witnesses, or at the mouth of three witnesses, shall the matter be established.

The number 5 identified with judgment/savation:

Joshua 10:26 And afterward Joshua smote them, and slew them, and hanged them on five trees: and they were hanging upon the trees until the evening.

1Samuel 6:4 Then said they, What shall be the trespass offering which we shall return to him? They answered, Five golden emerods, and five golden mice, according to the number of the lords of the Philistines: for one plague was on you all, and on your lords.

1Chronicles 11:23 And he slew an Egyptian, a man of great stature, five cubits high; and in the Egyptian's hand was a spear like a weaver's beam; and he went down to him with a staff, and plucked the spear out of the Egyptian's hand, and slew him with his own spear.

Luke 16:28 For I have five brethren; that he may testify unto them, lest they also come into this place of torment.

Matthew 25:2 And five of them were wise, and five were foolish.

The number 7 identified with Perfection/Completion of set / sabbath of harvest activity::

Perfected completed work of God

Genesis 2:2 And on the seventh day God ended his work which he had made

Perfect Completed set of all churches typified by 7

Revelation 1:20 The mystery of the seven stars which thou sawest in my right hand, and the seven golden candlesticks. The seven stars are the angels of the seven churches: and the seven candlesticks which thou sawest are the seven churches.

Completion (sabbath) of harvest activity is identified with 7 and the end of harvest is associated with the end of the world:

End of 7 years typified a sabbath and the end of harvest activity

Leviticus 25:3 Six years thou shalt sow thy field, and six years thou shalt prune thy vineyard, and gather in the fruit thereof;
Leviticus 25:4 But in the seventh year shall be a sabbath of rest unto the land, a sabbath for the LORD: thou shalt neither sow thy field, nor prune thy vineyard:

End of Harvest is the end of the world:

Matthew 13:38 The field is the world; the good seed are the children of the kingdom; but the tares are the children of the wicked one;
Matthew 13:39 The enemy that sowed them is the devil; the harvest is the end of the world; and the reapers are the angels.

The number 19 is identified with length of great tribulation:

19 years signified the length of time in which the spiritual latter rain harvest was concluded outside Chanaan during Jacob’s Day.

Acts 7:11 Now there came a dearth over all the land of Egypt and Chanaan, and great affliction: and our fathers found no sustenance.

Planting of gardens in Babylon and harvesting of Garden for captives carried away under Jehoaichin is also associated with 19:

The first Planting of gardens in Babylon and harvesting of Garden for captives carried away under Jehoaichin is also associated with 19 as 57 years has factors of 19 and 3. The first planting by the captives of Jehoaichin could have only occurred in Tishri 597 BC (see note below) to the last planting Tishri 540 for a total of 57 years. In addition, the first harvest by the captives of Jehoaichin could have only occurred in Tishri 596 (see note below) to the last harvest in Babylon (Babylon was destroyed October 10, 539 BC Feast of Ingathering) Tishri 539 BC for a total of 57 years.

Note: Sowing Time

Tishri, latter half (beginning about the autumnal equinox.) Cheshvan. Kislev, former half. Early rain due = first showers of autumn.

Jeremiah 29:4 Thus saith the LORD of hosts, the God of Israel, unto all that are carried away captives, whom I have caused to be carried away from Jerusalem unto Babylon;

Jeremiah 29:5 Build ye houses, and dwell in them; and plant gardens, and eat the fruit of them;

The last King of Judah Zedekiah appointed by Babylon in the Spring of 597 BC. Thus, the captives of Jehoiachin could have only planted their first Garden in the fall of 597 BC in Babylon.

The 19th Jubile and the year 457 BC:

Exodus 1447/1446 (Exodus) + 40 years =1407/1406 (entered Chanaan - the start of the fiftieth year count). The jubiles occurred every fiftieth year. The year 457/456 BC equals 950 year from 1407/1406 BC, which is a total of 19 jubiles. The 19th jubile signified the completion of the latter rain harvest.

Leviticus 25:11 A jubile shall that fiftieth year be unto you: ye shall not sow, neither reap that which groweth of itself in it, nor gather the grapes in it of thy vine undressed.

The year 457 BC was a jubile Sabbath (land rested). The harvest season contains a Sabbath 50 days within the Harvest Season (Pentecost). A 127 days later from Pentecost is the final Harvest Season Sabbath or Ingathering. A tropical year is 365.24218967 days. There are 901,417 days from 457 BC to 2012 AD. The factors of 901,417 are 11 (last hour of harvest) X 19 X 19 (land rested in Chanaan to End of Great Tribulation in Jacob Day) X 227 (Pentecost). - see link for study

The Completion of the Pentecost Harvest (typified by the sealed 153 fish in the net) would be in the year Tishri (fall) 1993 to Tishri (fall) 1994.

John 21:11 Simon Peter went up, and drew the net to land full of great fishes, an hundred and fifty and three: and for all there were so many, yet was not the net broken.

Tishri (fall) 1993 to Tishri (fall) 1994 year is the 13,005th (11,013 BC + 1992) year of the earth’s existence.

The factors of 13,005 are: 153, 17 and 5