If your airport has many airlines that compete on that route, then you should hold tight and wait (it's only October, and tracking fares over one month is not that long, even though it seems like it). It really depends when airlines can capably predict what the pricing should be in May 2016 without overly hedging their bets.....seven months in advance may be too far out for them to reliably price the fare, that's why sometimes you see some outrageous fares far in advance (airlines usually try to match what their competitors do on a certain route, so their software takes other airline pricing into account).
The short answer is, the best time to buy is when you're least emotional about it and you set a target in your mind (based on the info you got by tracking over many months) - once the fare meets that target, then go for it. Everyone has a different target, so that's why there's no single answer that works for all.
Check out http://www.itasoftware.com/ and look a month out to see how fares vary over time