Notwithstanding the provisions of Section 5533, with respect to any district formed after December 31, 1974, the board of directors shall at its first meeting determine by lot which three wards in a five-ward district or four wards in a seven-ward district, and which two wards in a five-ward district or three wards in a seven-ward district, shall have four- and two-year terms, respectively, at the next general election. Thereafter, at each biennial general election, a number of directors corresponding to the number whose term of office expires shall be elected for terms of four years. The terms shall commence on the first Monday after the first day of January next following

the election.