We used to get great deals waiting until about a month or a month and half before the trip to book, but that just doesn't seem to be the case anymore. The last few trips the best prices have been by far early on, more than 3 months before the trip. For our November trip, the prices went up pretty significantly around August the past two years. Most people going with us had to pay a good deal more than we would have if we had booked earlier, and several people that had not booked tickets are backing out due to the price.

If prices are going all over the place, and you see a reasonably cheap day, I would go ahead and book. Flights are a lot more crowded these days, and I'm not sure the days of waiting for great sales are over.