Interest in Standup

19M from NYC.
I've wanted to do stand-up since I was around 12, but I've never actually gotten on stage.
Over the last day I've started seriously writing material based on personal experiences (getting stopped by cops, stereotypes, dating insecurity, growing up Catholic, etc.) and I'm realizing I enjoy the writing process a lot more than I expected.
My biggest issue is I don't know when material is "good enough" to take on stage.

For comics who started in NYC:
How did you get started?
Did you just sign up for an open mic and go?
How polished was your first 5 minutes?
What clubs/mics are beginner-friendly in NYC?
Looking back, what do you wish someone told you before your first set?

Any advice is appreciated. I'm serious about giving this a shot, but I'm probably overthinking it.