When to shave

I am going for my first coolglide treatment this coming Saturday. I am having my buttocks and the backs of my legs done because of cronic ingrown hairs. If I do my own shaving how many days before my treatment should I shave? I had a patch test done and shaved three days before. I never did notice a lot of hair falling out but it did seem to grow back thinner than other areas after another full shave. Do you get better results with smooth skin or some stubble or even a little longer hair?