I have used DME more times than I can count at this point. I've had times as short as 50 mins from gate to resort, and I've had one time that it took 85 mins. The vast majority the time is right around 70 mins or so.
Figure it this way....
gate to DME area.....10-20 mins, depending on pace, and any stops (my time has been about 10 mins)
line to checkin.....0-15 mins, usually right around 3 mins or so if you don't have to go to the counter (my time...5 mins)
in the bus line...0-20 mins, depending on when the last bus was (my time...10 mins)
on the bus, waiting to leave.....0-20 mins, again, depending on whether you were among the first to board, or the last. (my time usually....10 mins)
ride to the resort....25-40 mins, depending on which stop you are. (my time, 30 mins)
As you can see, worst case scenario is about 115 mins. But that just isn't very likely. It really comes out to closer to 75 mins.
As far as the time needed prior to departure.....pickup time is usually 3 hrs prior to departure, give or take 15 mins either way. If flying internationally, it's 4 hrs.