When you get over to the USVI, you report your arrival using the CBP Roam app (there is a user decal fee listed in the app, and you enter a number to avoid this, but I can't remember what it is - search on this forum - we've figured this out in a prior thread). We have used the Roam app to report our arrival twice, and the first time, they didn't clear us until I called the office.
If you don't have a decal, enter 00000 (pretty sure it was 5 digits), and then continue - no problem.
Have fun!!!