I had one today and they said the same thing as what Mrs B26 said. 24-48hours in 50% of cases it will start labour. I have noticed significant more amount of tightenings since but not contractions and not regular but it must be doing something. She also said to me walk, walk and walk. I was only 1cm dilated but better than nothing and it has definitely irritated the cervix and uterus. I am going for a big walk tonight!!