We also went about that same time this year (arrived this year on the 12th of April). I agree with PP, Sunday was busy but the rest of the week was very manageable. We were able to do everything we wanted. And Easter is even earlier next year so that might also work to your advantage since we were there one week after Easter, the schools that are off the week after Easter were still on vacation that weekend. We talked to a couple of families from Washington State that were there on Spring Break starting on the 13th, but most everyone else is back in school by then.
Just FYI, the park was open 9-9 during the week (8-12 on Weekends) with WOC and Fireworks every night, but they were only doing Fantasmic on the weekends. I think the following week it went back to 10-8 hours so I would probably plan on that. Three major rides were in refurb and at least one additional one was scheduled to close the next week (Indy and it probably should have been closed when we were there since it kept breaking down).