Discuss with your charter company to make sure you have paperwork on board.

Check out of BVI (You and your "crew"). Can do 24 hrs in advance. I prefer checking out JVD.

Sail to USVI: If boat is registered with CBP can use ROAM app and accomplish online (US Residents).
If above not available, report to Cruz Bay (moor around point) . Dingy in (PFDs, Flashlight, portable VHF recommended) and lock dingy to right of ferry. Walk to Custom's office with entire crew.

Returning to BVI, check into BVI. If you report crossing into BVI waters prior to Customs opening, expect to pay "Over Time Fee".