https://www.buzzle.com/articles/acupressure-points-to-induce-labor.html
here is an article that will explain it better than i can. i have only used it once, but it worked. i started early thinking it would take a week or so if it worked at all. i started at 37+5 and went into labor and had her at 37+6. i dont know anyone else personally that has used it, so i cant say how well it works but it sure did for me that time. i have read that even if it doesnt start contractions it will still ripen and dilate your cervix and make baby descend in pelvis more, so it sure cant hurt!
i only used the thumb and index finger webbing one, but it must have been enough!