I know a lot of folks who are used to the hyper planning needed for Disney feel pressure to do the same at Universal, but it's not complicated at all. You have taken care of the major things like onsite stay with express pass and early entry. here are a few other pointers.
Find out which park is opening early to onsite guest when you check in. If it is 8:00 am be at the gate at 7:45.
The boats start running early enough to accommodate getting there.
If IOA opens early you should head straight to Hogsmeade and do Forbidden Journey, Flight of Hippogriff and Dragons challenge. Take in shops at Hogsmeade and then be on Hogwarts Express as soon as it starts running and head over to Diagon Alley. Ride Escape from Gringotts. Then catch the show at Ollivanders wand shop. If the young ones are into Potter get them interactive wands so they can so do the magic tricks outside the shops and at the magic trick sites in Diagon Alley and Hogsmeade.
You need Park to Park tickets to ride Hogwarts Express.
Reverse this if Universal opens early. The two Potter Parks are what's busy at both parks.
Have lunch at Three Broomsticks in Hogsmeade or The Leaky Cauldron in Diagon Alley. Counter service at both no need for reservations.
After you get your Potter fill I would start hitting the other rides. Minions ride is very popular can be a little wait at times even with Express.
You get really wet on Dudley Do-Rights Ripshaw Falls and Popeyes and Bluto's bilge rat barge and Jurrasic Park River Adventure if you set in the front. We save these for when we are heading to the resort so we are not hanging out in the park wet for rest of day.
Have a meal at Mytho's in IOA. You can make ressie easy on the Universal website.
Look at the maps of both the parks on the Universal Webste at the bottom of the page. Check out the lay of the land.
The parks are easy to navigate. Have a great time.
