Since most of the DVC resorts are owned by the members and not Disney, most won't be available until a member either trades their points into the Disney Collection (like
DCL or Disney hotels that are not DVC or ABD). 60 days out any unbooked inventory is turned over to Disney Reservation Center to sell. With the large number of point brokers, there may not be a lot of member inventory left at 60 days out other than the odd inventory like a few nights in a Bungalow or Villas at Aulani or a couple of nights here and there (usually not studios and one bedrooms). DVC does retain about 2% of each resort, but that may be needed for maintenance issues or to leave enough villas for point stays while they are renovating. New resorts like Riviera will rent out the unsold inventory (builders inventory) and that won't be available for points. There also might be some inventory from Disney buying back points that are for sale by the owners through Right of First Refusal. But if it is like 2008 during the financial crunch, Disney might not be buying back any inventory through ROFR. No need to buy it back if they can't sell it to a new buyer.
Depending on the resort, you could start to look for villas available for cash through Disney Reservation Center no more than 11 months out, but you might not find anything until seven months out or less. Some resorts are going to be very hard to find like Grand Californian Villas, or Grand Floridian Villas since they are small. Larger ones like SSR, OKW and AKV might have inventory available for cash sooner.