For district magistrate judges holding office on December 31, 1978, a full month‘s proportion of such a judge’s annual pay shall be paid for the payroll period ending on January 17, 1979, notwithstanding that such period is shorter than the normal payroll period; however, when any such judge vacates his or her office, such judge’s final compensation shall be reduced by an amount determined by subtracting the amount of compensation actually earned by such judge for service during the period commencing on January 1, 1979, and ending on January 17, 1979, from the actual amount of compensation received by such judge from the state for the payroll period ending on January 17, 1979. In the event that this act takes effect after such judges have received compensation for the above described payroll period, the additional compensation provided for by this act shall be paid as soon as practicable after the effective date of this act.