The Commissioner may, on finding either that the Department is unable to efficiently handle the replacement of license plates or decals or the renewal of registrations scheduled to expire during a specific month, or that persons seeking to secure license plates, decals, or registration renewals are, as a group, unable to do so without being substantially inconvenienced, declare a grace period for the replacement of license plates or decals and the renewal of registrations. The declaration of a grace period shall have the effect of postponing the expiration of those license plates, decals, and registrations scheduled to expire on the last day of that month to the fifteenth day of the succeeding month.