A property owner shall commence construction within 12 months of the issuance of the first zoning and/or building permit, as it pertains to the issuance of a variance. If a property owner has timely secured his/her zoning and building permits, however, does not commence construction on said permits within 12 months from the first date of issuance, then the variance and accompanying zoning and building permits shall expire. The Zoning Officer may conclusively presume that the applicant/property owner has waived, withdrawn or abandoned approvals and permits and may consider all such approvals and permits to have become null and void.