The legacy airlines (American, United, USAirways) release flights at 331 days. They don't release them in blocks like Southwest, Jet Blue, etc.
If you go to American's website and try to book a flight, it will show you the calendar and which dates are available. Right now it's up to August 18, 2014. August 19 and after are greyed out. Check it tomorrow and it should show August 19 is available. I found prices on day 331 are usually very high on the legacy airlines.