My recommendation for when you should purchase airfare is to buy when you are comfortable with the price! And then don't look back! Set up an alert which notifies you when there is a change in airfare prices and follow it for a bit. Airfares are so crazy these days, you just never know when you are going to get a good deal. So, follow it for a while and if there comes up a fare that seems reasonable, just buy it. You can also keep track of how many seats are sold on a particular route that you are interested in. If the plane is almost sold out, or pretty full, chances are there will probably not be much, if any, reduction in airfare for that flight. On the other hand, if it's still several months out and the plane is empty, and the fare that is currently being offered is about the same as it has been for some time, you are probably safe in waiting a while to see if they run a sale.