THats a hard one, I think its different for everyone! I've heard of them engaging at around 32 weeks and a few days before birth. I was somewhat engaged (can't remember now...) at 36 weeks and again at 38 weeks I progressed, but at 42 weeks she had completely disengaged, and a few days later only a little... That was an unusual occurance for her to not be engaged anymore, but thats what happened with us!