My laser tech said to shave as close as possible the day of, and that what I did other days didn't matter to them at all. I've never heard this recommendation before, and I can't imagine how what you do on days you're NOT there could influence the treatment... but who knows, I'm not an expert.
OK, and they did also say not to shave afterward until the skin wasn't sore/tender, but that was more for my comfort than a risk to the treatment results.