Charter bus passengers should not be allowed to board until departure time because:

1. The cost of the bus starts when the first passenger boards. It saves money to board as late as possible.
2. Passengers will be more likely to get on and off the bus multiple times before departing, raising the risk that they will miss the departure entirely.
3. Passengers should not be allowed to decide which seats to take until the bus is about to leave.
4. Waiting to load helps to prevent theft and vandalism.