Thank you for everyone's comments! Quick followup: If we start with IOA for Hogrids (which is a priority) during Early hours, should we do the rest of the IOA Harry Potter rides and then immediately switch over to US via Hogswarts Express? Or, is it better to stick with all the IOA rides for a portion of the day to minimize going back and forth?
Hmmmm, one day with EP... on Thanksgiving weekend.
I think I would get to IoA an hour before the Early Park opening time and head to Hargid's first. After that, use EP at Forbidden Journey. At that point, you'll probably have a bit of time before the Hogwart's Express opens up. You could use that time to ride Flight of the Hippogriff coaster (short, 'kiddie' coaster, but we like it for what it is), explore Hogsmeade, or start walking towards the next area of IoA you want to explore.
I think your decision will have to be based on your priorities. If the HP rides are a priority, you might want to take the train over to USO and ride Gringott's. At that point, I'd stay in USO and do everything you want to do there - that will likely take up a good chunk of the day. I'd pick a direction walk that park as 'one way' as possible, hitting the rides you want as you pass them. That's easy with EP.
Taking the train can eat up some time if you don't get lucky with the timing. EP helps, but if you just missed a train, it takes some time for the next one to show up, unload, load, and leave.
If HP rides are the priority, you probably will want to ride the Hogwart's Express back to Hogsmeade. If so, make the full loop back to the London area and ride the train back over to IoA. Once again, check your priority list - if Seuss is the next priority, head that way. If JP or Kong is the priority, head that way.
Also, during the day, I'd check the app for a virtual queue at Hagrid's and try to grab one for early evening. Trying to get the timing right might be difficult, but it's your best bet at trying to ride that twice.
I think the biggest slowdown you will hit in your day is food, so try to plan for off times. Or, if you see a short line somewhere and it's close to when you might be hungry, take advantage.
So, the key question is - what are your ride/attraction/show/food priorities?