Well, everyone's experience is different. But I'll share ours.
Chris and I LOVE Disney and WDW (obviously). We also love thrill rides and Harry Potter. So when we went to WDW last year in September, I added a day on so we could visit WWOHP. Here's how we did it.
Tuesday morning: Fly in early to Orlando, town car to Hard Rock Hotel. Check in, dump luggage, grab our park tickets and head to IOA. Your hotel room key IS your express pass. So even after you check out, it works until the park closes that night.
We bee-lined it for WWOHP, took it all in and took a few photos at the entrance and by the Hogwarts Express, then straight to Forbidden Journey. There was a posted wait of like 20 minutes. You need more time than that to navigate the queue and take it all in. So it was pretty much a walk-on.
Then, if I remember, we rode Duelling Dragons twice - once for each side. Walk-on. Then we explored all of Hogwarts, probably had a butterbeer, etc., then headed through the rest of IOA (we had never been before), via Jurassic Park (we watched the movie again right before we went), then Hulk (which turned out to be my favorite rollercoaster in the world). We used our room key to ride it like 6 times in a row, a couple of times in the front seat. (Caution: lockers are only free for approximately the duration of the posted wait time. We spent a small fortune on the lockers because we left our stuff in them while we rode 50 times. Well, ok, not 50 but you get the point.)
Then we might have gone back and ridden FJ again - I don't remember. Then the last thing we did before leaving the park was ride the 3 water rides. We knew we'd get wet, and we did. Very wet. Then we trucked back over to our hotel, showered and went to dinner at Margaritaville. (I think the park closed at 6pm that night.)
The next morning, we went back to IOA, rode FJ again, had a beer at Hogs Head Pub, and lunch at Mythos. Then Spiderman and a few more goes at Hulk, then over to USO. At USO, we hit all the big ones (Rip Ride Rock-It was closed for maintenance - boo). We did MIB, Simpsons, Jaws, Mummy, Disaster, Horror Make-up show, ET, had lunch somewhere, a couple of other attractions and shows, Mummy one or two more times, and we were done. It was about 4pm and we looked at each other and said "are you ready for some Disney magic?" Seriously, it is not the same at US/IOA. You will notice a difference in the team members' attitudes, cleanliness of the parks, etc.
I wouldn't say we were walking very fast anywhere. The Express pass (room key) did come in handy, as we walked right on everything. But I realize we may have been faster getting around than you and Mom will be. But it will be Nov/Dec and I doubt you will want to do the water rides. I also bet you won't do the thrill rides like Hulk and Mummy over and over again like we did. I really won't be surprised if you are "done" by the end of the second day. Especially if the parks close later than 6pm like they did for us.
So that's my story

(Oh, and I will add the only two things we didn't do that I wanted to do were Ollivander's and Rip Ride Rockit. The line was always about 20 minutes for Ollivander's and we just didn't feel like waiting, knowing what was going to happen inside (there are lots of
Youtube videos out there).