Within sixty days prior to July 1 in each and every year, the school board selection commission shall appoint, for terms of four years beginning July 1 next following their appointment, successors to the members of the county school board whose terms of office expire on June 30 of such year. In any county having five or more districts in which it is found by the school board selection commission that it is not in the best interest of the schools for the terms of the school board members from two certain districts to expire simultaneously and such terms have been so expiring, the commission may, on the next occasion thereafter for appointing successors to the school board members from such two districts, appoint the member from one of such districts for a term of one year with appointments thereafter to be made for terms of four years.