We're also checking into THV's on June 1st.
We're at Kidani right now, and when we checked in here we spoke a little with the CM at the counter. She said she's scheduled to do a stay at THV's in late May. Something like 8 CMs will be in her THV.
Their requirements of course are to check everything out from the unit itself, such as electrical (lights, etc) to water systems, and on to transportation, and so on. They're to try to have any requests, questions, or needs that a typical guest might have, in order to see if the new staff is ready and properly trained.
This is basically what
DVC has done for the openings of all the DVC resorts over the years.
While you might call this a 'soft' opening, it's actually a testing/training phase before the resort's actual opening. AFAIK it's only Disney employees taking part. I don't think it includes any real guests.