I'm an owner tied to the school schedule!
I've been able to get reservations everywhere at 7 months w/no problem. I own at SSR and AKV but I am not including booked-at-11 month trips below:
Spring Break - HHI and AKV studio (booked at 7 months). Added on a night at SSR about six weeks prior to a trip.
New Years/First of January - HHI and VWL (booked 3 months prior - got SSR immediately and had to waitlist for VWL, but it came through)
Early June - have gotten BWV (got preferred view at 7 months, had to waitlsit for the BW view, but it came through), OKW (with no waitlist), Vero Beach OVIR
Early August - got Vero Beach (garden view inn room), SSR, and OKW all about 6 weeks prior to a trip right after we bought in.
Late July - BCV, BWV (Boardwalk view without waitlisting), Vero Beach OVIR
Easter, Thanksgiving, and Christmas are busy - but points are very high and that seems to cut down on the demand.
The hardest time to book
DVC reservations seems to be early December and October/November (food and wine). If you are tied to the school calendar as we are, those are impossible times to travel so the possible lack of 7 month flexibility is not as much of an issue.