The director of personnel, under the direction of the commission and in cooperation with the county clerk, or county auditor, if any, and with the heads of the various departments, shall devise and recommend to the board of supervisors a standardized scale of wages and salaries for all county offices and positions in the classified service. The wage scale shall be graduated according to the duties performed, the length of service and efficiency records of the officers or employees, and the time of day or night those services are performed by the establishment of shifts. The supervisors shall consider and act in some way upon this scale at the last meeting of the board of supervisors in the month of October next following its recommendation, and if adopted it shall go into effect on the first day of January following its adoption, or at such other date as may be provided by law.