The first reply says it all. While IN GENERAL (or ON AVERAGE) one time is better than another, that does not mean it works for everyone or even the majority. The time of year of your flight, the time of day of your flight, the departure airport, and the arrival airport ALL factor into pricing.
What you SHOULD do, right now, today: Start stalking airfares for your travel dates and airports. Look at surrounding airports (however far you're willing to drive). Use tracking apps/websites (google flights, hipmunk, etc), but don't RELY on them. This far out, I would be looking at least twice a week if I'm using tracking apps, more often if I wasn't. Keep a spreadsheet of what pricing you're finding. If you see it at $500RT for weeks on end, then you find it at $200RT, grab it, don't look back.
You've got to get a baseline.