There's no reason to soak her before a shed. It could actually have the opposite effect that you would think it would. BPs generate their own "shedding lubrication", and soaking/bathing an animal that's in shed could end up washing away the natural fluids that help them shed on their own.
Just make sure her humidity level is where it needs to be and she has plenty of water to drink and she'll be fine. Good luck to you both!
If you haven't already, there's a fantastic write-up on the entire shedding process here: http://ball-pythons.net/forums/showt...edding-Process.
Best regards,
Eric