N.J. Stat. Ann. § 18A:22-4

The board of school estimate shall consist of the chief executive officer of the governing body of each municipality and the president of the board of education of the district ex officio, and two members of the governing body of each municipality, to be chosen by their respective governing bodies and one member of the board of education of the district, to be chosen by said board, all of whom shall be chosen during the month of January and shall serve for one year from February 1 and until their successors are chosen. Vacancies occurring in the board shall be filled in like manner for the unexpired terms.