This regulation shall be effective on March 1, 1977, and shall be applicable to all individual disability insurance policies (except those specifically excluded from the scope of this regulation) delivered or issued for delivery in this state on and after such date: Provided, however, That policies which have been approved prior to January 1, 1977, and which are not in compliance with this regulation may be issued until May 1, 1977, unless approval is specifically withdrawn pursuant to RCW 48.18.110.