N.J. Stat. § 40:43-16: Organization of newly elected officers

On the first Monday after the filing of the result of said election in the office of the clerk of the county, those who were elected members of the governing body shall assemble in some convenient place, and after each member thereof has duly qualified and taken his oath of office, they shall proceed to organize in the manner provided by law. All other officers chosen at said first election shall qualify within five days thereafter.