We did something similar to what the OP is hoping to do. However, we bought our original 150 point SSR contract from Disney. Still, the 7 month window has worked for us in our most recent holiday planning. We are staying at OKW March 12-17, 2006 in a 2-bedroom -- 150 points exactly.
I originally booked 4 nights at our home resort, SSR, 11 months out and then waited until the 7 month window opened up and flipped the ressie over to 5 nights at OKW. There was no problem at all.
FYI -- 5 nights in a 2 bedroom at OKW cost only 6 points more than 4 nights in a 2 bedroom at SSR.