It's easy so no worries! Depending on your airline you'll get off your plane in either Terminal A or B. You'll have to take a tram (easily marked) to the main concourse. Follow the signs for "Ground Transportation" in Terminal B. Magical Express is only in Terminal B. When you get off the tram you'll be on level 3 so you'll need to go down the elevators to level one once you are in terminal B - don't go down to level one until you are in terminal B. They are located on the opposite wall of the outside - you can't miss them.
You go through the queue and check-in so make sure you have your ME paperwork. If you don't its okay, not the end of the world (I forgot mine last trip and they were able to pull it up by my name) but it makes things go faster. They will check you in and tell you to go to another area where you will be directed to the appropriate line for your bus.
As far as time goes, it's anyones guess. It can be as quick as 45 minutes and as much as 2 hours. It really depends on the time of year you are going and the number of people taking ME. During marathon weekend in January ME was chaotic but ran very efficiently. It took me longer to wait in line to check-in for ME than it took to get to the resort with 2 stops. Even so, we were at the resort in less than an hour and we think it's a great service.
No worries, you will have plenty of time to get to your resort before your ADR. I would recommend carrying a spare set of clothes and swimsuits in your carry-ons in the event there is a delay with your luggage. Better safe than sorry.
