Not really going to matter I think as both parks will hit capacity both days, but I would do IOA and get there early like 6:30 am at least as they have moved early park entry to 7am for this weekend. If Hagrid is on list, go straight there and try to ride it 2x in standby, Forbidden Journey, then Hippogriff. Ride Jurassic early and try to get Spiderman/Kong when it opens as it will probably not operate until official park open. These are the rides that will get the longest wait times and you can easily get them done by lunch if early open at 7am. If you leave the park, I wouldn't come back until around 5, but they will definitely hit capacity this weekend, so you run the risk of not getting back in. I would call the main reservation number around 9am while waiting in a line and try to make a sit down lunch reservation for Confisco's or Mythos to give you a break out of the heat and not have to deal with mobile order. If you need AC, hit Cat in the Hat in afternoon. If you like water rides, bring appropriate clothing/shoes because if you ride Bluto or Ripsaw Falls, they are amazing, but you will get soaked! I would head back into Hogsmead after 5 or so to do some sightseeing, but I think that area will be slammed from about 10am-5pm.
USO day I would head straight to Diagon Alley and sign up for wand experience and get in Gringotts Line, hit Mummy as soon as it opens, hopefully before it goes virtual. I saw some crazy wait times for ET on capacity days. If you can snag any virtual lines either day for Hagrid or Mummy, go for it.