It would help a lot if you posted your origination and destination cities. Some airlines (like Alaska) sell one-way tickets that are half the price of a round trip ticket (instead of what used to be one way tickets that cost more than a round trip ticket.) If these airlines work for you, you could get a one-way outbound ticket now and a return ticket later on. Another option is to book a round trip ticket now with a return date within the 331 days, but change it later on and pay the change fee, if any. Finally, you could get the cheapest round trip ticket you can and just throw away the return, and book your return flght later doing the same thing. Just work out the economics and see what works best for you.