i had one they said it takes around 12-24 hours to work but within 10 mins i felt something.It was'nt painfull having it inserted just a little uncomfortable and kind of tingled a little when it began to work.I gave birth exactly 12 hours after having it.
It's sort of like a tablet with a string on ( said almost like a tampon) and it's going to be left in for 24 hours