Membrane sweep/Cervix stretch??

Heather
My doctor said in two weeks he's going to do a membrane sweep and stretch my cervix....has anyone had this done? What is it exactly and how fast does it bring on labor?? I'm not due til the 28th so I was just kinda confused....but he did say based on my last ultrasound baby is ready to go! Ahhh I can't believe it's almost baby time, this pregnancy flew by!