Whenever the Postal Service determines to request that the Commission issue an advisory opinion on a proposed change in the nature of postal services subject to this subpart, the Postal Service shall file with the Commission a formal request for such an opinion in accordance with the requirements of Sec. Sec. 3001.9 through 3001.11 and Sec. 3001.83. The request shall be filed not less than 90 days before the proposed effective date of the change in the nature of postal services involved. Within 5 days after the Postal Service has filed a formal request for an advisory opinion in accordance with this section, the Secretary shall lodge a notice thereof with the director of the Office of the Federal Register for publication in the Federal Register.