The operative date of this subtitle is: a date from June 2, 1947, to April 29, 1949, both inclusive, as specified by the insurer if the insurer filed with the Commissioner written notice of an election to comply with this subtitle on a date before April 30, 1949; a date from May 1, 1949, to January 1, 1950, both inclusive, if allowed by the Commissioner; or April 30, 1949.