The requirements of this chapter shall be applicable only to fasteners fabricated 180 days or more after the Secretary issues final regulations required under sections 5404, 5405, and 5407 of this title, except that the Secretary may extend such time period if the Secretary determines that an insufficient number of laboratories have been accredited to perform the volume of inspection and testing required. Upon any such extension, and every 6 months thereafter during such extension, the Secretary shall submit a report to the Congress explaining the reasons for such extension and the steps being taken to ensure the accreditation of a sufficient number of laboratories.