membrane sweep?

Abby
I'm 39 weeks I have a appointment Tuesday by that time I will be 2 days away from 40 weeks he said he'll induce me at 42 weeks but I was wondering can I ask him to try and do the sweep ? I mean if it doesn't work then wats the harm in trying anyways right? But I've never been checked and I tried to feel my cervix and it's just soft and I can barely feel it..can he  still do the sweep ? And if he does how long does it take to work ?