Hilton Head is our home resort. We bought 12-31-00, while we were at WDW. We called to make a reservation for June on our way home 1-02-01, at the Wilderness Lodge Villas and got what we wanted, a studio, for June 17-21. We decided to add on June 16 a couple of weeks ago, and was able to get that also. So we didn't have any problem at the 7 mo. window (actually 6 mos). We did go to Hilton Head in March to check out our home resort. It is very nice, have you been? I know it is hard to get a reservation there in the summer, so the 11mo. window is important if you plan to go there in the summer.
Good luck!!