We were there 4/16-23.
4/16-We arrived at the parks Sat evening and it was not really crowded at all. We walked right into WWOHP. Did Ollivanders in about 10-15 min.
4/17- No Crowds at all anywhere!! We were able to walk right into WWOHP all day long. No return tickets. Waits for things like FB/Flight of the HG were 60 min or less. My dd used the single rider line and walked on.
4/18- MOBBED! We arrived about 8:30am and only stayed until 1pmish. We planned on returning, but ended up at the pool instead.
4/19- Crowded, but very manageable. We spend the day at US and did everything we wanted to do. Rides/shows/character meet & greet.
4/20-This was our early day. We were expecting it to be mobbed so we arrived at IOA @ 6:15am for the 7am early entry. My dd was the first one to ride FJ. She was super excited! We stayed until about 2pm in WWOHP. Did everything we wanted to. Rides several times over, both of the shows and had lunch. Left and came back to US in the evening. Great!
4/21- We arrived about 8:00am to IOA. Walked on to all of the water rides. Could have ridden them multiple times with 10min or less wait, but the little one only wanted to redo the Bluto Bilge. Spent the rest of the day seeing characters and doing whatever caught our eye.
4/22- We had planned to skip the parks today or making a short day of it. I thought it would be a madhouse for Good Friday. Boy, was I wrong. The crowds were much lighter than the past few days. We saw the shows we had skipped earier in the week and went to both parks.
4/23- We didn't arrive until about 6pm. Everyone picked 1 thing they wanted to do. Walked on to disaster, and 10min wait for MIB. Then to IOA walked into WWOHP and got our butterbeers. DD rode FJ at least 3 times in a row with no wait and ds rode FOH 5 times in a row with a 5 min wait.
All in all, I was surprised by the crowds. I was expecting and prepared for much worse. We didn't stay onsite & didn't use express pass at all and never waited more than 30 min for anything we wanted to ride or a show.
I do want to add that we arrived at each park most days anywhere 30 min prior to 30min after sch. opening. I noticed that about 10-11am most days is when it seemed to get crowded. Then started thinning out about 6-7pm.
For us, there is not enough to do for 7 days exclusively at IOA/US. I was expecting bigger crowds and planned to take our time for everything. In the end, it was a great and semi relaxing trip!