Agree with all of the above. However, would like to add that depending on crowds and numbers of buses running, ME can take up to a half hour or so (maybe more) before you're even on the bus. Or it can take 5 minutes. Then, it also depends on whether or not your hotel is the first stop. Usually there's about 3-4 hotels per ME bus, and about 10-15 minutes per hotel (then 5-10 minutes or so driving between, give or take). So you're travel time getting off the plane to getting to your hotel can be anywhere from an hour to about an hour and a half/two. Then check in can take up to a half hour in waiting then actual checking in. Then you have to wait for the bus (up to 20 minutes), then its about a 10 minute ride to Epcot. When we go, we like to aim for three hours before making any definite plans, but it's possible you'll make it by 12. I'd aim for closer to 1 though.
Sorry if this is confusing, but we've done this a few times, and the timing with ME is so up in the air, that it really is anyone's guess as to when you'll actually be getting to your resort.