Appointments. The Board of Selectmen shall make appointments to a Board of Appeals, established pursuant in Chapter 40A of the Massachusetts General Laws and all amendments thereto, which shall consist of three members and two associate members, one associate to be designated by the Chairman of the Board to act in the place of any member incapacitated by personal interest or absence. The first appointments shall be made for one-, two-, and three-year terms respectively, and thereafter one appointment for a three-year term shall be made on or before the first day of March in each year. Associate members shall be appointed for two-year terms, the first appointments being for a one-year and a two-year term.