There's no timetable for when DVC offers rooms to The Walt Disney Travel Company to sell for cash. OKW, like all DVC resorts, is mostly owned by members not Disney. There are only a few ways that DVC rooms become available for cash.
Rooms from breakage are usually released about 60 days out. There can be some "anticipated breakage" where DVC speculates how many rooms will go unreserved by members based on past years. However, there have not been a lot of rooms left to release for breakage lately because many members are actually using their points instead of letting them expire and DVC graciously extended the expiration date on points that members living outside of the U.S. own. Those members are now able to travel here and they are using their surplus points!
Rooms that would have gone into cash inventory when owners trade their points out to ABD or
DCL just aren't there in large numbers due to limited offerings by those divisions in the last 18-24 months. Those are the rooms that you usually see available before 60 days out. But with no cruises sailing and no ABD trips booking for the longest time, members had no choice but to book resort villas or lose their points.
It's going to take a couple of years for the dust to settle. Meanwhile, only about half of Riviera is owned by DVC members and the new all-studio Grand Floridian building will open with 101 studios that are not member-owned. Those are more likely to appear for cash reservations than sold-out resorts.