Terms of office for Planning Board members shall begin on the first Monday in May and continue for three years. The terms shall be staggered so that not more than three terms expire each year. Whenever a position on the Plan Board becomes vacant, the Mayor and Councilors shall proceed to fill the position in accordance with Section 3.6(e) of this Charter. The Clerk-Treasurer shall publicize all vacancies and solicit applicants through the municipal newsletter if one is published, public notices, and other means prior to a person’s being nominated to fill such a vacancy.