Custody laws in Cali..

So i need some insight into custody laws in Cali.. In late March I got sole custody of my three kids with visitation for their father every 1st and 3rd weekend of every month.. So heres the thing hes already missed 2 weekends! Also court order says pick up is at 6pm and he has come around 9 to pick them up🙄 So I want to know if there has to be a pattern of missing his weekends in order to file for a revision of custody (or whatever its called lol). And if so how long does the pattern have to be? Thanks for the insight ladies. I appreciate it!