There' s two philosophies to consider. First, are hunters that like to be in the stand before daylight and 2nd are the guys that like to walk in when they can see so if they come upon deer they can get a shot or avoid spooking the deer.
I personally like to be in the tree at least an hour before daylight. If nothing else, it' s just a great peacefull time to be in the woods while you wait for daylight. You can watch falling stars and hear all kinds of strange noises. However, I have spooked deer stumbling through the dark.