My first was an induction; 3hrs. My second was an induction; 90min. Both with use of syntocin. My third labour was 2hr and it was spontaneous natural.

As for gestation; my first was induced at 38+5, the second at 37+6. So I have no idea WHEN they would have come had they chosen their own birthdays. The third chose himself and he came on his EDD.

From my experience I would say expect a relatively quickish labour but if you go naturally instead of induction then it could possibly be a bit longer than your second labour like mine was.

My midwife told me she always expects third labours to be the 'curve ball' labour. Something always goes completely differently to the first two - in my case it was that I was absolutely not dialated even a smidge until I had been having 3min contractions for hoooooooooooours unlike #1 when I was 1cm at labour induction and #2 I was 3cm at labour induction