At PSA, you have to start training within 6 months of interviewing. If you interview now, and are not able to start training in 6 months, it isn't a problem, you just have to interview again.
The RTP (Rotor Transition Program) is a great program, and the first pilots are just starting it now. Make sure to read the details about each program, as they are different. Envoy makes you use your GI Bill benefits, where PSA does not. If you prefer West Coast, then Envoy does their training there for RTP, PSA uses Pensacola, FL.