When we did our B2B, it was a few years ago, before Covid. We got a letter on our bed the night before the switchover telling us the options and procedures. Our home base was Barcelona. We had saved some things to do there during the switchover day and got off the ship and reboard later in the day, checked in and walked straight onto the Magic. Now, things are certainly different, but I would assume you will still get a letter telling you the latest steps you are allowed to take. We have another one coming up Sept., 2022, so we will see what we are allowed to do.
Good luck!,