The members of the council in office when this charter becomes effective shall continue in office until noon on July 1, 1961 and until their successors are elected and have qualified. At the first election under this charter, which shall be held on May 2, 1961, seven council members shall be elected. The four candidates who receive the largest number of votes shall serve for terms expiring on November 30, 1965 and the three candidates receiving the next highest number of votes shall serve for terms expiring on November 30, 1963. Thereafter, successors shall be chosen at the regular municipal election for full terms of four years.