Because you aren’t going park-to-park, seeing everything you want to see will actually be extremely doable. UO does a nice job of keeping the parks open long enough to reflect crowd levels (just double check there isn’t a corporate buy-out or Grad event going on…otherwise you should have 12+ hours to explore each park).
For IOA…
Hagrid’s should be your first stop because of long lines AND breakdowns. However, if they’re offering Virtual Line that day (check the app when you get on property), sign up for that ASAP and instead hit Kong when you first walk in. Then maybe Hulk…I believe these two lines get much longer than Velocicoaster on average. Any water rides are best in the morning or evening to minimize lines. If you’re looking for a sit down meal I’d look into booking a lunch at Citywalk. Lunch time is generally more crowded than dinner time so taking that time to eat is just biding time until crowds peter out a bit.
For USF…
A lot more simple, go from Rockit straight to Gringott’s. The rest of the day is yours, and I’d use the same lunch tip here too (the in-park food outside of the Mardi Gras tents isn’t great anyway).
Remember that lines close when the park closes, not before. If one particular ride on your top list has too long of a wait all day, save it for the last 5-10 minutes of the day. That’s a good way to get extra park time (you’ll be in line/on the ride after closing) and the line moves faster once Express/disability pass lines are shut down.
Of your must-do’s, all but Hagrid’s and Poseidon have single rider lines. They may not be available at the time you go there—this just means they’re too long and Universal is doing you a solid and letting you know you’re better off waiting with your family in the standby line.
The front plaza of each park generally opens ~1 hour before the park does (including Early Park Admission). Any time within that window would be good to arrive, but the second it hits 8am (or more likely 9) the lines in the parking garages and security gates will start getting pretty heavy.
Overall you’ll have a good time! With all day in each park knocking out your top 5 shouldn’t be an issue as long as you have a little patience to bite the bullet on a few longer queues. Have fun!