There's a fair amount of misremembered/revisionist narratives about when places closed down and how much that correlates with the scale of their outbreaks. California was quite on the ball. But NY closed earlier than many states, including other West Coast states like WA & OR.
Here are the dates in each state when either stay-at-home orders were implemented or nonessential services were closed, whichever came first. (In NY, these happened on the same day.) 
To be clear: NY effed up and even 3 days (difference between CA and NY) can matter a lot. But for many reasons, when places shut down and how bad their outbreaks were is likely to be a messy correlation.
And, yeah, it gets more complicated if you look at partial measures, what cities were doing before statewide actions, etc. But not necessarily in a way that makes the narrative simpler, e.g. NYC was taking a lot of half-measures also.
