(a) The negotiations between a municipal employer and a municipal employee organization shall commence at least one hundred twenty days prior to the expiration date of any current collective bargaining agreement subject to the provisions of sections 7-467 to 7-477, inclusive.

(b) If, within fifty days of the commencement of negotiations concerning the terms of a current collective bargaining agreement, or within eighty days of the certification or recognition of a newly certified or recognized municipal employee organization required to commence negotiations pursuant to § 7-473a, a collective bargaining agreement has not been approved, or either the municipal employer or the municipal employee organization has not requested the mediation services of the State Board of Mediation and Arbitration, said board shall appoint a mediator in accordance with the provisions of § 31-97.

(c) Either the municipal employer or the employee organization may request the mediation services of said board at any earlier time than that established in subsection (b) of this section, provided the mediation services are requested in accordance with the provisions of § 7-472.