SSR is the largest resort by far, so that makes it easier to get (and it is even a possibility for pretty last-minute trips).
OKW and AKV-kidani are also fairly large resorts that can have availability on shorter notice.
the smaller resorts and resorts that are in walking distance from the parks can fill up before the 7 month window opens.
it can vary by time of the year - the period from oct to new years' is extremely busy for DVC bookings and requires more lead time if you hope to rent a villa.