There is no way to know exactly what is available other than looking at it in real time on the DVC website.
Out board sponsor has something that gives a general idea a few times a day, but things with DVC change so often that until you can book, you just never know!
Also hope DVC keeps breaking 3rd party availability tools. You may not see it as a big deal but it does put extra stress on the servers causing slow downs and possible issues for those looking to actually use the system.