Your options are
DCL bus, car rental, or private limo. Obviously, there are many car rental companies and limo companies. I'm familiar with Happy Limo, FL limo, Tiffany limo, etc. ALL of the limo services are cheaper than DCL.
With a limo service, the driver will meet you at baggage claim at your scheduled time. He will take your luggage to the vehicle, and drive you to the port. You are allowed a 15 minute stop at a grocery or
Walmart if you desire. He will drop you at the ship's porter area where they will take your bags. You do need to attach the DCL luggage tags after you pick up your bags at baggage check. Do not put them on before you get on the plane because if you do, DCL may pick them up....and if they find that you haven't purchased transfers, they may try to charge you for the baggage handling! I'm only aware of that happening once, but why risk it?
The port opens to incoming traffic at 10. If you arrive earlier, you will have to park and wait...and may be charged extra for the waiting. It is about 45 minutes from MCO to the port. If your plane arrives at 8, you might want to delay your limo till 8:30 or so...which will allow your luggage to be unloaded, etc. but won't get you to the port too early!