Organizing recurring tasks so they stop living in the owner's head

The owner of our small shop—that's me—remembers when to reorder supplies, follow up invoices and check weekly reports. Staff ask because the information isn't written anywhere. I've begun moving recurring work into a shared checklist with an owner and due date for each task. What belongs on a simple operational calendar versus a procedure document? I want people to act confidently when I'm away, not replace my brain with a hundred-page manual.