Where a person is carrying on the business of a dealer in second-hand goods on the appointed day and application for the registration of himself or, where he is carrying on that business in premises in the county occupied by him, for the registration both of himself and of those premises is made within four weeks of that day it shall be lawful for him to carry on that business, and, where he is carrying on that business in premises specified in his application, to carry it on in those premises, until the issue of his certificate of registration.