It's no secret that the Thanksgiving holiday weekend is one of the busiest travel times of the year. It's also among the most expensive when it comes to airfare.

Joe Raedle, Getty Images

So, if you're planning to travel by plane, don't procrastinate. Buy your tickets now. If not, it could cost up up to $5 per day.

"The two busiest days to fly are the Wednesday before Thanksgiving and the Sunday after the holiday. They also happen to be the most expensive," said Rick Seaney, co-founder FareCompare. "If you're traveling on those days, airlines have absolutely zero incentive to discount. In fact, they have much greater incentive to raise prices. So, if you're looking to fly on either one of those days, buy your ticket right away. Starting about the third week in October, you're going to start adding $5 a day every day you decide to procrastinate."

Around Thanksgiving, the price of airline tickets goes up very dramatically especially during that last week leading up to the holiday.

"What happens is the more people wait, the more difficult it is to find a seat on the most convenient route, so they wind up taking one or two stop routes," said Seaney. "Typically, the price points for those holidays are set up to be about 25 percent higher than normal. Then, Wednesday and Sunday actually get another 20 percent on top of them. The good news is airline ticket prices in general are up only one percent. The bad news is last year was the highest we've tracked in eight years."

So, how can a traveler get the most bang for their buck?

"The absolute best day to fly is Thanksgiving Day or the Monday and Tuesday before the holiday. If you can avoid Wednesday, that will save you. On the way home, if you can wait until Tuesday, that will be less expensive than heading home on Sunday or Monday," said Seaney.

"People want to get home Monday without having to take a vacation day and the airlines know that, so Monday is expensive too."