Its 330 days from the return flight. You can fool the computer before this by ticking flexible dates and you will see the later flights and the cost on a calender. I did this once we were 330 days form the outward flight, however on the last page of the booking it threw up a computer system error and I was resigned to wait.
However at 329 days from the return flight I got a booking confirmation e-mail, unfortunately they had me down for full payment not the deposit I had picked so I was able to cancel it and re-book.
Everything is now booked, Flights, 1st night in Bewleys airport hotel, car hire and Saratoga springs. My CC is screaming foe mercy!