Time in and time out is the invoice. A parent who returns twelve minutes late is a conversation nobody wants, so the record has to be automatic and visible rather than a note somebody wrote down at the desk.
The mix decides the capacity. Ten toddlers and ten eight-year-olds need different supervision, so a single maximum number describes an afternoon that may or may not actually be staffable.
Who collects matters more than anything else here. Named adults, agreed passwords and what happens when somebody unexpected arrives is a safeguarding record, and improvising it at the door is not acceptable.
The regulars are the business. A parent who comes every Thursday is worth recognising with a pass or a prepaid block, and knowing who those families are turns occasional trade into something predictable.