I had never been to Universal either before buying the military passes for 2021. We found that having the EPs for both check in and check out day was enough time for us to do both parks in 1.5 days. I checked in very early usually ~0545. Also, we found being first (or close to first) in line when the gates open will get you onto Hagrid’s in decent time and then you can hop right over and do VC, knocking out those rides where you don’t have EP.
Here’s a link to our first day from one of our 2021 jaunts: 12 Apr 2021 - USF