Unfortunately, your kid got the short end of the stick. April is literally the last batch or wave of decisions. In our case, my kid was admitted EA in December and was extremely SO happy knowing she would be attending one her top choices, if not her top choice. Roughly 50% of the acceptances are sent out in December. And then the other 50% of acceptances are released in later waves.
But around here in CA, personally I’d trade the probability, even high probability, of getting an earlier decision in the windows of December (before Xmas), February 1 or March 1 instead of 100% getting your answer from the UC’s in mid-to-late March with zero possibility of an earlier decision, unless you receive one of the few elite Regents scholarships (announced in February). Or Ivy Day is late March too.
I’d like to know sooner, if possible, and if deferred, then just wait. We have to wait for everything in life. It’s just one more thing to wait for, if deferred. That’s my $0.02 on the UMich process.