Not for NJ, but usually (if there is no significant delay from handlers/customs/border) and you are not parked very far from terminal, and you dont have tons of baggage, then you can count 15-20 minutes from pax arriving terminal, to engine start.
But this estimate is heavily dependant on variables (slots/location/time of season/pax willingness to depart quickly) - theoretically and not counting Russia, then our usual estimate is 30 minutes.