I agree, it will be easiest to get a GV at OKW however it still may be difficult at the 7 month window. Assuming you own at an on property location that doesn't have a GV, your best approach is to reserve a studio plus a 2 BR at the 11 month window. Then at the 7 month window, try to change to the 3 BR GV. If it's not available, you may still want to change to OKW in a studio and 2 BR (less points and more room). You can, and should, wait list the 3 BR GV.
You'll have to decide how to approach it. You could call day by day at the 7 month window and take the days available for the 3 BR, wait listing the rest. Of course you'll then have to decide whether to keep the 2 BR plus studio if you don't get all the days. If you're set on the 2 BR, I'd call day by day and cancel the corresponding day on your existing reservation if you're successful. Then if you don't get any days, simply wait list. You can always go back later and cancel the partial reservation if you need to then make a new 2 BR plus studio reservation. If you approach it this way, your chances are pretty good if you aren't trying for a holiday, Premier or Magic Time.
Of course, you could work out a swap with a member who has a home resort there. Or you could rent out your points now then rent from an OKW owner at the time, improving your chances of success.