In California, can parents transfer property to children without property taxes increase if it's not the child's principal residence?

I have a concern about California Prop 19, which will go into affect on February 15, 2021. I understand that under the new law, if property is transferred from parent to child, the child must use the property as their principal residence or the property tax will be reassessed. I want to know if the property is transferred before the law goes into affect, will the child be required to live in the property or will the old rules will stay in affect.