I tried this (as well as anything else I could think of lol) but it did nothing for me. I was told to do it in cycles, so stimulate them for 5 mins then stop for a minute or two then stim for 5mins etc.. But if that doesn't work try longer intervals. I used to sit on the lounge doing this all night and nothing.. so glad that no one was home or came to visit me lol It was the funniest sight, plus it was in summer so really hot, so i'd only be in my underwear lol
I was told that a good way to bring on labour is to sweep, sideways, pretty energetically. But I never got around to trying it.
HTH