The existing highway district commissioners shall appoint a qualified elector to serve as a highway district commissioner for each of the subdistricts of the new highway district. The commissioners shall provide each of the commissioners appointed to the new highway district with a certificate of appointment. Each appointed highway district commissioner shall take and subscribe the official oath, which oath shall be filed in the office of the newly organized highway district commissioners. The first commissioners shall serve until the next highway district election as specified in section 40-1305, Idaho Code.