Airline sale activity usually picks up at the end of August. I would check back on AA.com at that time. Flights to Mexico aren't terribly expensive, so I don't think you're going to save yourself $100s by waiting but I guess every little bit helps.
What kind of rates can you get through AeroMexico? We're going in early June and I've seen $443 round trip on AA from Austin. In my mind that's a great price, but maybe not.