As a way to control labor, the system should have a way to prevent employees from clocking in early. I worked with a system in the past, where I could control how early the clocks allowed an employee to punch in. (An error message would appear saying they are not scheduled to work yet, and would post the time the employee is scheduled to work.) Currently we have employees who clock in up to an 45 min before their scheduled start time - simply because they arrived to the location early. Granted, the GM should be controlling this, but in a busy shop this is not always possible. Prevention at the clock is key.