I'm going to assume you know about departing with DME. So...to use RAC..
You need to be all done with your transaction no less than 3 hrs before your flight departure. For instance..if your flight is at noon, you have to have your bags checked and boarding passes in hand, no later than 9am. If your flight is at 8am, you won't be able to use RAC...simply because the RAC counter opens at 5am. So..anyone with flights before 8:30 is going to basically have to take their bags with them, back to MCO.
With that in mind....
You take your bags, and ID, down to the RAC counter at your resort. They will check your ID, then weigh your bags and tag them. Say goodbye to your bags here..you don't see them again until you get to your home airport. Then, you will get your boarding passes issued.
Depending on the time you can either take your carryon bags with you and head out to the DME bus stop...if the bus is due soon. But, if you have hours to kill, you can leave your carryon bags with Bell Services and head off to enjoy the last few hours of your vacation. Return to the resort about 45 mins before your designated pickup time. By the way...that pickup time is the time the bus leaves, not when you should show up. Be out at the bus stop, carryon bags in hand, ready to go, about 15 mins before your pickup time.
It may take Bell Services a few minutes to get your carryons out, so leave enough time.