Within thirty days after the receipt of an application, the Zoning Inspector shall either approve or disapprove the application in conformance with the provisions of this Part. All zoning permits shall, however, be conditional upon the commencement of work within one year. One copy of the plans shall be returned to the applicant by the Zoning Inspector, after he marks such copy either as approved or disapproved and attests to same by his signature on the copy. One copy of plans, similarly marked, shall be retained by the Zoning Inspector. The Zoning Inspector shall issue a placard, to be posted in a conspicuous place on the property in question, attesting to the fact that the use or alteration is in conformance with the provisions of this Part.