IMHO
Get to the park half hour before opening and be at the front of lines for when they do open.
HP will get very busy, so a beeline there might be worthwhile. I have seen lines 90 minute wait by 9:15. Express pass doesn't count toward the HP area, so no loss in that. Remember though, people staying at the Universal resorts get early entry, so HP will already be busy at 9 am.
We always hit park early as less busy, and typically by 1 PM leave and go back to rental house for afternoon. Many times we will return for evening after dinner.
I haven't been the first week of April as we are in school, so can't speak to how busy it will be.
Make sure to take in the horror makeup show. It is bit silly but entertaining. On Terminator, we like sitting up close toward the front. The "ending" is bit more intense, but you do lose out on some of the peripheral happenings. Disaster is especially entertaining if someone in your party can be selected to be one of the actors in the show that they shoot. Dragon Challenge is basically 4 rides - front and rear seat of each train is very different experience. Try them all if you like coasters.
Hope these thoughts help
