Anaheim USD lets out May 26th, unless it's necessary to extend the calendar to make sure they have the minimum number of days in the school year, in which case it extends to June 3.
Garden Grove USD - last day of school is June 1st
I don't recall what other local cities are nearby off the top of my head but most of this is searchable online.
So, it looks like most kids are out of school before your trip starts.