My hospital notes count mine as from when I was 3cm onwards (established labour). So going by those notes, my labours were 4 hours for DD1, 50 minutes for DD2 and 5 minutes for DD3.
I don't count it as that though. I count labour as when the contractions started. So that would be 9 hours for DD1, 6 hours for DD2 and 3 hours for DD3.