I know you want to get it ahead of time but it doesn't seem worth it. On Tuesday we waited about 15 minutes at Magic Kingdom for DAS and it was done. It still might be better to do it on your first day at the parks until they figure things out with the virtual option.
If you have had DAS in the past have you tried just saying that and asking to reactivate it for your trip?
We didn't use the virtual option but just telling the Guest Relations host at MK we needed to reactivate it was enough. No other questions.
Back at the parks today (Epcot) and the app is working to book DAS times. First up is Soarin.
To book on the app you just pick the attraction and it tells you the return time. You then add the party members who will be riding with you and that's it. Really easy.
To summarize our experience today. Nothing different than the DAS of the last few years. You get a time based on the current wait. When you use it you can get another. No limit except the closing of the park. Genie+ can be used with it to get additional return times and you can overlap the times...
Be honest, who hasn't imagined being able to grab one of those iPad to get themselves unlimited Fastpass? :p
Hopefully the pumped in smells are faithful to the real space station.