I think I might be tempted to leave my bags with Bell Services at the resort and head straight to a park for opening. Instead of taking them all the way to DTD (by bus?), then having to get a transfer to another resort to get to a park (DTD does not run buses direct to the parks) and then having to get another bus back to my resort to get picked up for DME.
The only snag then is you will have to check in your bags at MCO, but that may actually be quicker than all the bus transfers you will have to do otherwise?
If you have a car then I think doing the DTD check in works extremely well but I guess you might not if you are considering DME.