If you can't contact anyone at the school yet, you can get a few basic supplies until school starts.
- lunch containers, if it's full-day, and water bottle
- pencil case with a few crayons and pencils - don't go overboard with pens and markers, because the class may have rules about them
- large, sturdy plastic envelope/file with closure - I used to keep one in the backpack to transport notes and permission forms to the teacher, return work sheets, etc. It made it so much easier to find them and keep them from being crumpled at the bottom of the backpack
The school list will probably set out all the stationery needs, and things like indoor shoes or slippers, and boxes of tissues, that they request for each child.