Pre-Covid: main (early) seating gets early breakfast (about 7 or 7:15 am depending on the dining room you were in for dinner the night before). Passengers doing the express walk-off with their own luggage will already be lined up waiting for the port authorities to clear the ship for debarking. By the time you finish breakfast (~8 to 8:15 am), they have usually started letting passengers off. You may have to wait in one of the lounges until they call your luggage tag color (this can be port dependent, depending on how much space is available for the luggage to be displayed in the terminal for pickup; I think there is more space at PC than in Miami) or you may be able to join the queue to debark directly once you have had breakfast. They don’t want you to return to your room after breakfast, so you will take your hand luggage with you to the dining room. At PC, we are usually off the ship shortly after 9 am (we do main dining as well) and have collected luggage, transferred it to a waiting bus, and arrived at either MCO or our WDW hotel (we’ve done both from PC at one time or another) by 10 am.
The unknown here is whether things will be much the same post-Covid.