We were upgraded after we received our docs. We got a call from TA notifying us that free upgrade had been offered and did we want it. We were also told new cabin number. We said yes, we wanted...and she asked us to cross out old cabin number on luggage tags and write in the new number. Luggage was sent to our new room without any problem. We got the upgrade about 10 days before our sailing date.
We also had a trip where we picked up documents at the port. Thus, we didn't have the Disney luggage tags. I did put ID tags on the bags, and told the porter at the port the situation. He whipped "blank" tags out of his back pocket and put our stateroom number on those tags.
Kathryn