At the next general election of directors of a district which has been divided into director divisions, the electors of the first division shall select the director then to be elected on the board, and if more than one director is to be selected, the second division shall select one, and so on in numerical order, until, as the terms of incumbent directors expire, all the divisions are represented on the board, and thereafter directors shall be elected from the divisions in rotation, as their respective terms of office expire: PROVIDED, That if following the numerical order of director divisions will result in any year in one division having more than one director and one division having no director, then the numerical order of the divisions shall not be followed for the year or years in question but the electors of the next highest numbered division without representation on the board of directors shall select the director then to be elected on the board. If such a district is organized but has not yet held an annual election of officers, it shall, at its next annual election, select directors for three, two and one-year terms respectively, and if the district is managed by a board of three directors, the first division shall select a director for the three-year term, the second division shall select one for the two-year term, and the third division shall select one for the one-year term, and thereafter their successors shall be elected for three-year terms, respectively. If the district has five directors, the first and second divisions shall each select a director for the three-year term, the third and fourth divisions shall each select one for the two-year term, and the fifth division shall select one for the one-year term, and thereafter their successors shall be elected for three-year terms respectively. If the district has seven directors, the first, second and third divisions shall each select a director for the three-year term, the fourth and fifth divisions shall each select a director for the two-year term, and the sixth and seventh divisions shall each select a director for the one-year term, and thereafter their successors shall be elected for three-year terms respectively.