BVI Ferry schedules can be found here - https://bestofbvi.com/bvi-ferry-schedules/?from=Virgin-Gorda&to=Anegada

Smith's Ferry does indeed go from Virgin Gorda to Anegada (and back) on Wednesday's and Friday's. 7:15am departure from the government dock in Spanish Town.

I would make sure to call them ahead of time to confirm and let them know