Trying to guess the best day of the week or even hour to book your airline flight can be a daunting task. There are numerous websites that will compare and contrast prices.

To simplify your task, Hopper recently did a lot of the legwork for busy travelers. Here are some suggestions of of the best lead time to book a flight during upcoming, busy holiday dates:

Easter: book at least six weeks in advance (or the week of Sunday, March 1).

Fourth of July (US): book at least four weeks ahead (or the week of Saturday, June 6).

Labor Day: book at least five weeks ahead (or the week of Monday, August 3).

Christmas: book at least eight weeks ahead (or the week of Friday, October 30).

More useful tips can be found in this article about airline travel, courtesy of LifeHacker.