With night work, I don't use mirror up, but if you did, I believe the Nikon intervalometer would not work as it would only open the mirror when it fires.
With longer exposures, 30 seconds or longer you can skip mirror up as you will not see any blur from the mirror opening. In fact even with 10 second shots or 15 second shots when I work the Milky Way, I don't use mirror up as I find it makes no difference.
Paul C