No, it is not legal. Labor law (such as the Fair Labor Standards Act, or FLSA) requires that employers keep accurate time records, pay employees for *all* time worked, and pay overtime as applicable. What you describe is illegal: your employer may choose to not let you start working until 8am if they like (employers have free discretion to set hours of employment or work), but if they let you clock in and begin working prior to 8am, they have to track the time and pay you for it. If you are working without being paid for it, you could contact the department of labor to file a complaint.