Membrane sweep

I am 38+4, due July 10th. I had an ultrasound at my appointment today because I have been measuring small. Amniotic fluid was at 6.2 which is close to being low (5 or less). The doctor did a membrane strip/sweep to try and get the ball rolling sooner. Has anyone had one before? How soon might contractions or labor start? I am scheduled for a stress test and another ultrasound on Saturday.