I too think you should stick to the 5:30 time you have now.
Your thinking is a bit off with getting to the resort. Yes the actual ride there is about 35-45 mins, however you have to account for getting checked in to actually get on the bus, the wait for the bus which could be up to 20 mins. as well as getting everyone loaded. Then there is the factor of which resort is dropped off first. Your ME bus will be hauling people for 3 different resorts. Obviously the first to get off will hit a time frame of about 1 1/2 hours to 2 hours from the time the plane landed.
(so that already puts you at 4:30)
Next you have to check into the resort, this can take up to 15 mins or so on a fast day. If you check in online you may shorten that by a few mins but not a lot less. Then take your bags to the room and head for the bus to wherever you want to go, remembering you may have to wait 10-15 mins for a bus.
(that puts you at 5:00 or a bit after).
And finally is the bus ride to the place you are going, should be another 15 mins or so depending on where you are going and from where.
So when you break it down, I wouldn't have an adr no earlier than 5:30 and to be safe I would do 4 hours after I land.
Good luck and have a wonderful trip!