I'll start off with a little disclaimer. While there are often general trends in wait times, you can't really predict what wait times may be. HOWEVER, this would be my guess.
Here are some variables (or me rambling... one of the two):
#1
Springtime Surprise Weekend - This will see the biggest uptick in crowds. I wouldn't expect anything insane crowd-wise, but the crowds from the race will increase as you get closer.
#2 Spring Break - Lucky for you, spring break will be finished for most of the US. There will be a few stragglers, but those will likely be somewhat offset by the families opting to wait until summer to vacation after just having a break.
#3 Easter - You'll be visiting quite a bit after Easter, but there could be a few vacationers who chose to visit for a long duration or tried to avoid the holiday and will be checking in around the time when you are. I think the influence from Easter will be pretty negligible, with the bulk of any influence during the beginning of your stay.
Putting all of this together, I would see the beginning and end of your trip being the busiest, with the middle possibly being the least busy. As stated, however, "predicting" crowds is pretty much a guess and can't be done to great accuracy.
Thrill Data has some pretty good forecasts due to how long they've been collecting wait time data, but even that is not always accurate. Overall, you'll likely see pretty average crowds throughout your trip. Hope you have a great time!