Anyime you want to stay at one of the non-
DVC resorts during the last two months of your use year (except those options you can get via Interval International or the Lake Buena Vista Trading Company), you must call and make the reservation at least 61 days before your use year ends.
For example, let's say your use year is December and you want to stay at the Plaza over Thanksgiving. You can do that only if you call MS and make the arrangements no later than September 30 (because your use year ends 11/30 if you have a December use year).
If you wanted to stay anytime that isn't in October or November, it wouldn't matter when you called to make the reservation. The only "limitation" would be availability at the destination resort.
The reason for the rule is that MS has to rent out DVC rooms to get the cash to send to the destination resort to pay for your stay. Availability at the DVC resorts is often limited within 60 days of arrival and MS needs some time to turn your points into cash. MS has to use your points before they expire, the same as you would!
There are some special rules for late deposits to II that I am not totally familar with so if you want or need to do that, you might post a separate question and our resident II experts will undoubtedly help you out.
Good luck!
