The sun sets around 7:41 on April 20th. In the past, I've been rolling out of there with truck and trailer at around the 6:30pm mark, to continue the cleanup back at home.
Unless you left much earlier, I'd advise against a NYC show. Could be a 2 hour drive in on a Saturday night, if there's hellish traffic. But from the Denville Train station, you can have a relatively painless entry into NYC...takes about 1:20 to get to NYC Penn station, and another 20 minutes to make your way to a venue.