I’m not sure anyone knows the definitive answer to this yet.
I don’t know when the remaining nights of a room-only reservation is normally charged if you do on-line check-in.
I’m DVC, and we always check-in in person, because we’re coming from the U.K., so need to collect magic bands and they don’t text to U.K. numbers. When we have cash nights, I think the cost was charged to our CC each day, and we paid it at check-out.
As long as the room is paid for, you should be fine. And as long as they have a CC on file, they can charge the cost of the room.