when is everyone's spring breaks falling next year?

So uh, already booking our trip for next year soon, April 21-29 or April 29th-May 7th. Our spring break falls in late march and I plan on taking my son out of school for 5 days. Easter next year is April 16th. So do you think the crowds will fall by about the 21st? or would you wait until the 29? Or will it matter much? I'm thinking it won't matter much, aiming for 21-29 again. And this will be the second time we go where both my kids' birthdays fall while we're there