This does matter, but the answer depends on the facts and circumstances of the alleged offense. First, just because school is not in session or it is late at night does not mean that the police can’t give you a school zone ticket. In fact, the opposite is true. A school zone violation does not depend on the time of the day. In that sense, it is a strict liability offense, meaning you were either in the school zone or not. Each town must properly enact its school zone statute pursuant to the law, show proper passage of the ordinance and map measurement. Of course the State must be able to prove your intoxication in order to convict you of school zone. Also, the State must provide all the above mentioned documentation as it pertains to the proper passage of the school zone ordinance to prove the case, but it must be requested.
Whether school is in session only comes into play when the defendant is pleading guilty to the underlying 39:4-50. Usually, the police issue both a conventional DWI and a school zone summons. In certain circumstances, the prosecutor has discretion to dismiss the school zone if the defendant is pleading guilty to the underlying DWI charge. He can do this, for example, if there is no accident involved AND school was not in session. This could be an attractive alternative for some defendants because the school zone offense carries stiffer penalties including longer loss of license and additional (heavy) fines. If you choose to go to trial, you go to trial on both the 4-50 and the school zone. In that case your exposure is pretty high. So school not being in session is an important consideration, but it doesn’t mean the ticket gets dismissed automatically.