N.J. Stat. Ann. § 19:29-4

The judge shall appoint a suitable time for hearing such complaint, not more than 30 nor less than 15 days after the filing of the petition, and the contestant shall cause a notice of such hearing, with a copy of the contestant's petition, to be served, in the case approval or disapproval of any proposition is to be contested, on the Secretary of State, the county clerk or the municipal clerk, as the case may be, who caused the proposition to be printed on the ballot, and in all other cases on the incumbent at least 10 days before the day set for trial.