No need to soak her at all. Ball pythons who aren't already having troubles shedding/have stuck shed should never need to be soaked. She will shed just fine with 70% humidity!
It's actually counterproductive if you soak her before a shed, because it washes off the oils that their body built up to prepare for the shed. (Where did this soaking before a shed rumor start from?)
9 days without food for a 5 month old is also totally fine. But all my BP's now and in the past have eaten during shed no problem. Only some bp's refuse to eat when in shed.