My son is a CS major at Cal. He did not take any CS classes in high school. So the summer before college, he took an online programming course in Python (Coursera and Udacity have great options) which is much better preparation than CS 10 for CS 61A. CS 61A was difficult for him since many students taking the class had years of programming, but he caught up quickly and is now a EECS Honors Degree candidate.
He also took Math 54 first since it’s required for CS, taking Math 53 later, and the order didn’t matter.