The salary of council members shall be established by ordinance, but no member of council at the time of the enactment of any ordinance increasing such salaries shall receive the benefit of any such increase during his then current term of office. Any change in the salary of members of council shall be effective commencing with the terms of office of members of council elected at the next regular municipal election occurring not less than l2 months after the passage of the ordinance providing for such change.