We went at 8.45am and were not disappointed. If you are keen on photography you will want to go when the light is best, in winter we were told this was anytime between around 8am and 11am. The canyon wasn’t busy and we had the most fantastic guide that allowed us some rare freedom, the opposite of our situation in Upper Antelope Canyon the day before. We visited in February and after having heard so many stories about the insane crowds we were thrilled with our experience. According to two different guides that we spoke to the month with the lowest visitors is January (although note that the canyon closes for a couple of weeks in this period). In the warmer months the tours are almost always booked solid and you will be sharing this canyon with so many more people. The best time to visit is definitely in winter if you are looking to avoid huge crowds.