contractions! how long do I time them before heading to L&D?

RQ
How long do I time them?
Quick update:
Contractions were on the scale from 1-10 10 being the most painful 😭 and 1 being the least painful 😕... my contractions were at a  6. I downloaded the contractions app to time them they were 3 minutes apart and lasting 70 seconds and the app said to go to the hospital so I thought maybe it wasn't time because it didn't hurt much so I went in shower and then drove myself to the hospital I was 6 cm 90% effaced and they asked if I wanted epidural. I was undecided but decided to have it because on the last ultrasound at 38 weeks my baby's head was measuring almost 12 cm and just in case I ruptured it was recommended.. I'm here water broke at 11:45 and are waiting to deliver my baby girl 
Update: baby girl was born last night 1/23/2017 6 days overdue, weight 9.62 lbs 21 inches...
Things got a little too ugly and I been having lots of bleeding but she's big and healthy and I'm getting there.