You can go as long as you are happy and healthy FJ, of course that would be sooner than later if you were concerned that something wasn't right. There is no limit that they will stop you and pin you down for an induction, either you keep saying no and will go into labour spontaneously, or you can keep saying no then one day be monitored and something will be picked up and they will want to do something or you can agree to the induction. Take your pick Your choice hon.