We go to Seacrest on 30A the last week in February which might be the beginning of college spring break as well. As far as I can tell, we don't get the spring break college crowd on 30A -- or any of their activities, am I correct? I've never seen any of that where we are or on 30A. I think you get mostly families in the area in March/April for their spring break from school.
April for me is a little chilly in the water, but kids seem to be able to go in any time. Our kids went in (up to their knees) between Christmas and New Years and went in the pool, too, for brief periods.
We were there one year in April and the weather was very warm on some days and then we had a cool day or two as well.