Average time, from gate to resort, runs at about 75 mins. You could very possibly make an ADR that is at 11:30ish. But, if your flight is delayed, then you will have issues. And for the group that is arriving at 9:30?? Probably barely doable.
If you arrive, ontime, at 8:20, you will most likely be at BWV by 10ish. Those arriving at 9:30 will get to BWV by 11ish...again, most likely. It will take about 15-20 mins to walk from BWV to the restaurant in Epcot, depending on which one it is. So, those arriving later would have to drop their bags and head directly to Epcot with you.
I seldom make any ADRs less than 4.5 hrs after my flight arrives. The one time I did, I was supposed to depart at 8:15, arrive at MCO by 11:15. I had somewhere to be at 1:30. No problem, or so I thought. I was staying at BLT, the function was at the CR....a short 10 min walk would get me to where I needed to be. BUT.....our flight was cancelled due to mechanical failure, and we never left Boston until 11....just about the time we should have been landing!!! I got to the CR just as the function was ending!!!
So, plan accordingly.