You require employees to arrive ten minutes early to prepare for the start of their shift. Do you have to pay them for this extra time?
Under the Fair Labor Standards Act (and likely state law as well), you must pay employees for all hours worked. This includes the time they are required to be on your premises, even if they haven’t begun their “regular” duties. Preparing for work—if it must be done at work—will be considered part of the employee’s continuous workday.
You are certainly welcome to have an attendance and tardiness policy that requires employees to be at their desk or assigned location and ready to work exactly when their shift begins, and to discipline them if they are not ready. But if you require employees to arrive earlier to ensure this happens, you’ve effectively extended their shift by that amount of time and will need to compensate them for it.