No idea. My midwife and I differ in how we think about this, but I still don't know where to call it.
Timeable, increasingly painful contractions from 2am until about 8:30pm Sunday, when they spaced way out again. They continued throughout the night but the spacing/intensity chilled out enough to let me sleep. Monday morning they were lighter; around 10:30 we DTD and went for a walk and they picked up again enough to make the car ride to the chiropractor pretty hairy. By 1-2pm they had clearly shifted into something more than what I'd experienced to that point. ~4pm I had a contraction that I had to get on all fours and vocalize to get through, and vomited and shook when it was over. Called midwife, she got here at 6pm and I was 9cm, went to 10 as she examined me, had my baby at 7:33pm.
In all of this, my contractions never became regular. My midwife considers Sunday a day of prelabor, but I don't know if that's entirely true- I had bloody show several times and believe there were cervical changes happening. They very obviously were on Monday.. I'd been sending her updates throughout the afternoon, but until I called her and she heard in my voice that it was on, she was waiting for me to get to a 5-1-1 pattern which was never going to happen. I am apparently one of those that dilates with irregular contractions.
So anyway- anywhere from about 41 hours to.. 6 or 7, lol. (Love this thread, btw.)