You have two choices- if you want them to disembark your luggage, you put it outside your room ( locked) before midnight on the last night. Sometime during the night they will take it down to be offloaded. You will be assigned 'color tags ' a couple of days before, and on the last morning, they will start making announcements-
"those with green luggage tags may now depart from the gangway on deck 2" etc- you will go through customs with your declaration, then out to a large customs hall where you will look for your luggage in the green section, then you can go.
Guest services can tell you by the color tag you have ,which time slot is allotted to you. If you want a later/earlier time just ask them to change it...
If you want to do the self assist then just hang onto your luggage.
Those doing self assist will be the first group called to disembark- they will
just announce when you can leave. You have to take your own luggage down on elevators to the gangway, walk through customs with it, give your declaration form to the customs official and then you can go... it's not exactly a free for all, but you might have to wait for an elevator for a while.
The windjammer is open for breakfast on the last am up until around 9.am IIRC.