I always make it a point to carry my luggage off the ship personally. The entire color bag tag debarkation process is about the luggage, not the passengers. If you carry your luggage off yourself, you can leave when you want. I just debarked the Millennium in Barcelona a couple of days ago in the very first group and was at my hotel by 8:45 am. Getting off early means no wait for a taxi and no crowds in the baggage claim area.
Further you never lose control of your stuff, which is a huge benefit. I would always pack a carry-on with enhough stuff to get you through the first 24 hours in addition to anything valuable you do not want to check with the porters when embarking the ship.
In this way, you can start enjoying the cruise immediately without having to wait for your luggage to be delivered to your cabin. Board, have a great lunch and then hit the Jacuzzi with no worry.
Have a great cruise!