"The seventh month of the Jewish calendar is the month of the Feast of Tabernacles. John 1:14 speaking of Jesus as the Word, says: 'And the Word became flesh and dwelt among us, full of grace and truth.' The word 'dwelt' that is used here is the Greek word “skenoo” which literally means 'to tabernacle'!
So, when God came to earth to tabernacle among Men it appears that He timed His arrival in the Bethlehem manger to coincide with the Feast of Tabernacles. That was only appropriate, for the Feast of Tabernacles is the most joyous of all the Jewish feasts. It is, in fact, their feast of thanksgiving."
The Feast of Tabernacles is in late September or early October for his birth, but his conception was around December the previous year. (See website listed for calculation.)