If you are an owner at the resort, you can make a reservation at 9:00 a.m. ET at 12 mos. out from arrival date. So July 2009 can be reserved now.
If you are trying to make a Staroption exchange, you can request an exchange at 9:00 a.m. ET at 8 mos. out from arrival date.
For lots more info., see the Starwood FAQ at the top of the board.