Good one, Boss! Well, for me, I don't believe in having a strict policy on log-in and log-off timing. Generally, it happens only in IT/BPO companies. It's not very effective to have such a strict policy for sales/marketing-oriented companies. If we expect employees to come in on time, they will also expect to leave on time, which is rarely possible. So, I believe it's better to restrict employees with their job/tasks rather than with timings. If an employee has been assigned some work with a certain TAT (turnaround time), the employee will automatically arrive and depart on time.
However, there are always exceptions. If you find anyone going out of hand, you can counsel them or warn them with a positive circular.
Regards,