Shoot practice drills on the 8’ box and set them up like it’s on a 9’ box. So your working on the same thing (if you want to work on the same thing) that can be good sometimes. Not every time.
As the other responses stated. Just go play. Play play play
Work on fundamentals. Preshot routine-table size is irrelevant. Lining up over the ball correctly, hitting the spot on the CB you intend to hit. None of these have anything to do with table size. You can learn to be a world champion in a 8 or 9 foot box. If you pay your dues and have talent you can be a world beater learning and playing on a 8’ box. If you just pay your dues you can still be a hell of a player only playing on a 8’ box.
9’ tables don’t make you play better-you make you play better.
The box size NEVER made the player. Never has never will.
Good luck
Fatboy