At the regular municipal election to be held in 1990, the three (3) candidates who receive the highest number of votes shall be elected for four-year terms, while the two (2) candidates who receive the next highest number of votes shall be elected for two-year terms. Beginning at the regular municipal election to be held in 1991, and every four (4) years thereafter, two (2) members of the board of aldermen shall be elected to serve for four-year terms. Beginning at the regular municipal election to be held in 1993, and every four (4) years thereafter, three (3) members of the board of aldermen shall be elected to serve for four-year terms.