The DME routes are not the same every time, so there's no reason to assume that Bay Lake would be the last stop.We are staying at Bay Lake (which I think is the last stop on DME) and our flight arrives at 3:00 pm so. My wife and I are hoping to have a couple hours at MK to do 3 FP+ attractions and feed the kids dinner before heading back to the resort. Our kids will be 3.5 y/o and 13 months old at the time of our visit so we want to get the 13 month old to bed on the earlier side (7:30 pm'ish). Thus, getting to the resort faster than DME is of interest to us if we can make it work.
Honestly, between your flight time, the age of your children, your planned bedtime, and the fact that you'll need dinner, you really shouldn't plan on doing any park time that evening regardless of how you get to your resort. It's going to be more hectic than it's worth. Won't be "magical" at all.
Not to mention the fact that you'd have to sit around MCO's baggage claim if you're not doing Magical Express, which can be 45 minutes all on its own.
My kids are similar ages (3.5 and 8 months on the last trip) and we learned when the older one was small that pace matters more than anything. It's the entire key to a successful trip. Slow down. Make travel day about getting everyone to the room safely and in bed at a decent time.