The amendments to subpart A shall become effective upon publication in the Federal Register May 3, 1996; Provided, however, That in any case where a hearing has begun or has been completed prior to said publication, the proceeding shall be conducted pursuant to the rules of practice in effect at the time the proceeding was initiated unless the parties stipulate in writing or orally for the record that the proceeding be conducted in accordance with §§ 50-203.1 to 50-203.12.