Whenever a regulation is in effect pursuant to § 915.51(a)(1), the committee shall issue one or more exemption certificates to any person who furnishes proof, satisfactory to the committee, that his avocados of a particular variety are mature prior to the time such variety may be handled under such regulation. Such exemption certificates shall authorize the person to whom the certificates are issued to handle, or have handled, only that portion of his avocados of the particular variety which the committee has determined to be mature. The committee shall adopt, with the approval of the Secretary, procedural rules by which such exemption certificates will be issued and the avocados covered thereunder may be handled. Exemption certificates shall be transferred to the handler of the avocados covered by such certificates at the time the avocados are delivered to such handler.