A town committee shall be selected by each party in each town, in accordance with the provisions of sections 9-382 to 9-450, inclusive, not later than July 1, 1956, and thereafter at intervals not greater than twenty-six months. The terms of town committee members shall start on the first Monday following the date for the primary, unless otherwise provided in the party rules, except that the terms of all members shall begin and end on the same day; provided, when a town committee increases its membership as provided in § 9-393, the party rules shall specify the day upon which the term of all the new positions created by such increase shall begin.