Dear Hina.1661,
Before your make up the policy and circulate it with the employees, kindly note that, as you are making a policy, which says, that late coming will not be tolerated and deductions will be made. In short, you are asking for the employees to respect the in-coming time, at the same time, if your management has a style, where the company work for them starts only in the evening, then most of the people, will be extending the out-going time. So the moment you press for standardization on the in-time, the employees will standardize the out-time, if this does not suit your industry, a flexi time module needs to be implemented..
Think, Speak with the managment, analysis the outcomes and then plan your adapt policy.
Regards,
Ashutosh Thakre