You have until May 1 to SIR however depending upon the school, she may want to lock in her housing and many will not allow you to submit your housing request until you SIR. First come housing is common with the Cal States.
My son’s applied to the UC’s and CSU’s. CSU’s will usually notify you by the end of March and the UC decisions are out by March so my son’s made their decisions in Early April. If your daughter is waitlisted, she still needs to SIR to another campus until she hears about the waitlist so again the absolute deadline should be May 1.