I always freshened the baits at 11AM and then got in the stand. All too often its been found that surprising a bear on a bait while its still dark makes them very, very cautious and they tend towards being nocturnal then. For bear that were still at a bait when I needed to leave after dark I carried a small bell. I’d get the bell out and give it just a soft “tinkle” when the bear wasn’t directly facing me. That would alert a bear. A second soft tinkle would move the bear off the bait a hundred feet or so allowing me to quietly come off the stand and slip out in the opposite direction the bear went.
Bears have amazing hearing but seem to have a hard time focusing on small sounds coming from up. This doesn’t mean they won’t respond to sound coming from above.
I’ll add here that if any bear is on the bait or is approaching that has cubs, you’ll want to be darned CERTAIN that said bear with cubs has left the area BEFORE you come out of a stand. Remember, bears climb.