You will meet the Carnival Rep at the baggage check claim area. Your ticket stubs will have a transfer voucher which this person will collect. You will then be escorted to a bus to take you to the pier, The driver will be loading your bags
onto the bus and offloading them at the pier. (Make sure you have your apporpiate ship luggage tags on your bags.)
Once you get off the bus a Port of Miami baggage handler will put your luggage in a big bin that a forklift will load onto the ship. He should have a passenger manifest, so he can look up your name and will have extra baggage tags.It is a good idea to give these gentlemen a tip !!
There may be two ships in port, so make sure you are at the right check in area, your bus might drop passengers at both ships - in that case, the driver will place the bags in different holds below the bus.
You then walk inside the terminal, go through a metal detector just like an airport, and follow the lines to check in, get your sail and sign card which is also your room key on the newer ships - if you are sailing on a Fantasy Class ship, they still have older door locks with plastic keys that look like a 1960's computer punch card., then you follow the lines to board the ship and your are there!
Your bags should start to arrive within a few hours - sometimes they are quick and sometimes they are slow. There are 2000+ passangers with 2-3 bags each - that is a lot of luggage! You should have the bags at your door by 7:00pm at the latest.