We were just on this cruise. We went back to the ship from Magic Kingdom just after the fireworks. At the front gate they had a big sign up to tell you were the
DCL buses were. Very short walk and they were essentially loading and heading out. Very quiet - all the kids slept on the way back to the ship. They have a late buffet onboard till 1am.
One note - the park passes and fast passes that we were given on the ship didn't work. They seemed to be expecting this at the gate as they had replacements waiting. We had 3 fast passes on each but no way to track....so I just tried mine for a 4th (on a ride with no wait line) ....and it worked....so not sure if they made a mistake
Also - when you plan to go to your bus in the morning - Disney is extremely organized. The lines snakes through the ship but it moves extremely quickly. You have to go through customs but they were quick.
So would I would say is....don't stress, it works effortlessly. Just make sure your kids get a good night sleep the night before. The morning was all dads in the buffet making trays to take to the cabins at 5:30 am