We usually book the flight a few months after booking the resort. Pay attention to the fares though, even after you book. My DH was able to call Southwest & get a credit of $150+ when they dropped the price about 3 weeks after we booked our flight. Yea- credit that we can use for our next Disney trip! It pays to keep checking back & compare, compare, compare. Thanks to a tip here, we decided to check Southwest out of BWI, which is about another 1-1.5 hour drive for us- we normally fly out of Dulles by AirTran or Jet Blue, but we definitely saved by driving just a little farther.