The governing board of a school district whose average daily attendance is less than 3,000 may, by affirmative vote of a majority of its members, adopt the procedure set forth in Article 6 (commencing with Section 45240) of this chapter. The motion or a resolution for adoption of the system shall specify the date that the provisions of Article 6 shall be applicable to the classified employees of the district, which shall not be later than July 1 next following the date of adoption.