Don’t worry about trying to accomplish any ‘academic’ work! This is a completely new environment for your children, so I spend the whole first week (and much of the second) just getting them used to classroom procedures. In our classroom, we have children who attend different days, so my first two or three days are almost exactly the same. (More detail on that later.)
Remember, children don’t automatically know what to do. Tell them, and know that you will have to tell them many, many times. Be positive, be patient!