If you have reservations for a afternoon ferry can you take an earlier one?

Sometimes. You can call and ask, or arrive early. If there's room, they will accomodate.

If there's room yes

If they have enough room they will out you on an earlier one no problem. Shouldn't be an issue now there should be plenty of room

Yes if their is room in the ship

They're pretty flexible with that as long as there's room on the ferry. Also they will work for you if you miss one too.

I am almost always able to get on an earlier ferry.

I believe so. They have a"stand bye" Lane

Yes especially in the off season but call ahead

If they have availability, but ask when you drive up to the check-in booth.

Yes in off season. Best to call ahead. In summer it is harder. Always call before you are in Falmouth.