KayB,
You're off to a great start with the state. I remember with our class, they couldn't start homestudies because they didn't have any SWs available who could do them. Mine ended up being done by one of the supervisors. It ended up working out great, but still. Aren't all these things supposed to be worked out before the classes begin?
I would say hold off on the diapers, but if not getting a pack in each size couldn't hurt. If you can't use them, I'm sure you can find someone who can.
My son came home from an emergency foster care home and he came with enough diapers to get me through at least a week or two. My FD who I picked up from the hospital came home with enough diapers for a month. The nurses fell in love with her and felt bad for her situation.
Yash