N.J. Stat. Ann. § 18A:12-9

Of boards consisting of 5 members, one shall be appointed each year for a term of 5 years, of boards consisting of 9 members, 3 shall be appointed each year for terms of 3 years, and of boards consisting of 7 members, 3 shall be appointed in the first year and 2 shall be appointed in each of the 2 following years of each 3-year period, each for a term of 3 years, except the members of the first board of any such district, who shall be appointed for such terms, as shall, as soon as possible, result in all members of a 5-man board being appointed for terms of 5 years and the terms of one member expiring each year, or all members of a 9-man board being appointed for terms of 3 years and the terms of 3 members expiring each year, or all members of a 7-man board being appointed for terms of 3 years and the terms of either 3 or 2 members expiring in each 3-year period. All members shall serve after the expiration of their respective terms until the appointment and qualification of their successors.