How long were you at 3cm??

My first pregnancy, my water broke at 37+6 and after 21 hours of labor and over 3 hours pushing, she was born at 38 weeks.

Currently, I turned 37 weeks today. I have been having contractions since Wednesday last week and they had put me on the monitor for a few hours on Saturday and was 1.5-2cm by the time I left. I was also loosing my plug in bits since then. Today, at my 37 week check, she has dropped more, but I'm at 3cm and my cervix is still pretty high, but I know that can drop right before, and I have still been having contractions. My OB doesn't think I will make it to my next appointment.

How long were you at 3cm if something similar happened with you? I'm also strep b positive....again, so once I get to 4cm I need to be admitted for iv antibiotics again.

Just for fun, the picture below was last week. The blue was from Tuesday at 36 weeks and the red was from Sunday at 36+5 weeks.