You can put your luggage outside your room the last night, or not, as you wish. It's just easier to put it out, that way you don't have wrangle it yourself the last morning off the ship. Just pick it up in the terminal.
Generally
DCL wants everyone off by 9:00, that's when they will start urging any stragglers toward the door. 9:30 is the absolute latest I've read of someone being onboard. Remember, they only have a couple of hours to clean/turn the ship for the next group (who, undoubtedly want to be on "as soon as possible")
From what I've read, Concierge will be escorted to the front of whatever line is onboard exiting the ship, but at that point you join everyone else getting off the ship, claiming bags, and going through customs.
Are you doing a B2B Concierge/non-Concierge combo? Are you asking about turnaround day?