Since
DVC is sold to operate at capacity year round, DVC is almost always completely booked when you check in (at least the points inventory - CRO may still have their inventory). The question is "how fast does what book" and that is the $10,000 question.
Generally speaking, small resorts (VWL, BCV) book before large resorts (OKW, SSR).
Specialty units in high demand book more quickly (Grand Villas, BWV Standard View or Boardwalk View, 2Q 2 Bedrooms at BCV).
After Grand Villas, Studios are reported to booked quickest followed by Two Bedrooms with One Bedrooms booking last.
Traditional holidays (Easter, Christmas, Thanksgiving and New Years) and early December book quickly. Epcot resorts in particular book quickly during Food and Wine - and the other resorts book quicker than you'd expect for October. Special events (from non-Disney controlled Jersey Week to the Disney Marathon) can mean resorts book faster.
The waitlist changes at 30 days, and 30 days is the cancellation point for not putting points into holding, so sometimes you can find unlikely availability on short notice (and sometimes you can't).
Sometimes this will mean you call at 12:00 for a Boardwalk Standard View Studio for New Years Eve eleven months to the day and are out of luck. Or you can call while you are there deciding to extend your stay by a day and get an SSR One Bedroom.
But you'll hear plenty of stories about people who got BCV during Food and Wine a mere four months out. And stories about people who went on the waitlist for BCV during Food and Wine eight and a half months out.
We always stay "home" - but if we were the "want to try all the resorts" type, I'd book home, intend to stay at home, and then see what was available at seven months. Maybe I'll have my pick of resorts, maybe not. Maybe next year I'll get different choices. What I'd try not to do (and we are talking about trying a different resort for one night next trip) is get my heart set on something.