Rick Seaney published a post on his blog whether procrastinators are more likely to get a better deal.
His analysis is:
I can’t disagree more: shopping early doesn’t necessarily mean buying early. I always recommend starting to shop 4 months before departure.
Why 4 months?
I have noted in many articles shopping too early is a bad idea and 4 months before departure — for domestic travel — is a good starting point:
Airlines start activity managing seat prices
Southwest Airlines booking window is open forcing prices down on competitors
Likelihood of catching one of the 3 or 4 big sales of the year (less this year)
If you follow the crowd and procrastinate (as recommended in this story) you will fall right into the hands of the airlines. They know everything about your shopping and buying habits, when you want to shop, where you want to go & the days and times you like to travel. They use this information to charge you accordingly — follow the crowd and you’ll pay more.
I would add the following addition:
At about 4 months (if I have that much notice), I can buy a ticket on the airline site (and get the booking bonus if any) then register it with Yapta.
If the ticket price goes down, I can get a voucher for the difference (I fly United which will do that).
If the ticket price goes up, I have gotten the best deal.