We do one before school begins & then again after school starts.
I hated repeating myself so....
Before school - It is more of a time for the kids to see where the classroom is, what I look like & to get a sense of the room. They can find their desk & see where their things go. I take supplies that they bring w/them.
After school - We call this "Keys to Success". We go over everything!!!! From our daily routines to homework. I give them tips on homework & how to help with reading, spelling & math at home. I give them a folder with all of this info & then I give each parent who comes a homework coupon to thank them for coming. We have a hard time w/parent participation. Usually the parents who come aren't the parents I need to reach.