At any time after April 11, 1961, and before January 1, 1966, any company may file with the commissioner a written notice of its election to comply with the provisions of this part 3 after a specified date before January 1, 1966. After the filing of such notice, then upon such specified date (which shall be the operative date of this part 3 for such company) this part 3 shall become operative with respect to policies thereafter issued by such company. If a company makes no such election, the operative date of this part 3 for such company shall be January 1, 1966.