For me it was 3 tsp, but it doesn't always trigger labour...most of the time it doesn't from what I've read. It took 6 hours. But I was 2 weeks overdue and it probably was a big coincidence anyway.

I wouldn't have anymore tonight if it were me, 4tsp is probably the limit I'd go to.

Just remember, it often doesn't work, but that doesn't mean anything, always tomorrow, or the next couple of days I know that's the last thing you want to hear though