It's a tradition for me. Every 'Holiday Break' I fly to St. Louis to be with my family for the holidays. Usually I wait until the last-minute to book my travel (yeah... I'm a huge procrastinator).
Expedia has some tips for the best time to book your holiday vacation.
For Thanksgiving, the cheapest flight are booking between October 29th and November 13th where you can save about 20%. Cheapest deal to fly is on Thanksgiving day where travelers paid about $100 less than other days.
The best time to book for Christmas is between November 23rd and December 9th. Travelers save about 15% and the cheapest day to fly is Christmas Eve. Flying out on the 24th saves $100 compared to traveling the Saturday before the holiday. December 21 is predicted to be the busiest travel day leading up to the holiday.
Source: Expedia