For peak-season travel, especially closing in on the travel dates, I usually don't see fares drop again.

If it's about 3-4 months out, and it's not a particularly high demand route/date, then I see fares bounce around a bit, subject to various airline promotions and other carriers matching them.

What I tend to do there is watch all of the flights for a given day and take note of whether most or all of them are offering seats in the lowest fare bucket. If they are, then I wait around for a fare sale and usually get one. (I tend to do this on routes I know, so I kind of know what the typical Southwest or Frontier promo fare will be and whether my preferred legacies tend to match.) Just booked a fall ORD trip a couple weeks ago...it had been showing as $200 R/T from MCI for all fall dates (a historically high fare) and dropped to $99 R/T (a more typical off-peak promo fare, initiated by WN and matched by AA a day later).

It's when you see most of your possible itineraries start selling into higher fare buckets that you know you need to make a decision. Then, even if a competitor runs a promotion on that exact route, your desired flights probably won't change at all. Those $49 each way seats I booked were only available on the flights that had the $100 each way fare before. A different flight that was at $152 (an insanely high fare on this route) remained at $152 during the promotion.