Originally Posted by
JerryFF
The lowest fares require a 21-day advance purchase. Then there are 14-day, 7 day, 3 day, and walk-up fares. The answer to your question depends on how fare in advance you will know your schedule. If you will be making your final plans at least 14- or 21 days in advance, you should wait until you know for sure what you are going to do. If you are really making last minute (i.e., less than 7 days in advance) decisions, go ahead and buy them now, as the $200 change fee is less than the fare difference.
Lots of asterisk with the information here.
While the cheaper fares may require 21 day advance purchase, and then 14, or whatever, this is only one part of the equation. There needs to be availability - just because a low fare has a 21 day advance purchase requirement, it may not be actually available to purchase up to 21 days prior to travel. This constantly changes.
Also, it's not so easy with the change fee. Change fee is $200 plus any fare difference. So if you buy a $250 L fare, say, and you change, there needs to be an L fare on the flight you are changing to, otherwise you pay the fare difference in addition to the change fee. So that's definitely something to consider.
My suggestion is, if possible, to try and really figure out farther in advance what weekends you can travel. Then book the lower fares for those weekends. If you can't, you need to figure out how often the changes will happen, and decide whether you are better off to buy in advance and pay the change fee when necessary, or wait until your schedule is known and then buy the ticket at the price at that time.
On the other hand, this may be a time when WN might be the better Carrier to fly (all other things being equal). Note that WN also charges for fare difference. However, if you can pay $290, say, for WN and $250 for UA, but have to pay a change fee, UA is cheaper for you.