There is no "advantage" to any particular time of day if your biorhythm doesn't line up. The best time to practice is when you have your best concentration and motivation. That can be "learned" for first thing in the morning for some but not all. I really do not believe that we are all created equal and have the same "chances". There are differences in our drive, constitution, intelligence, musicality that all have to be balanced. I believe that natural light is a power that goes far beyond medicine and intellect. The more natural light that we are exposed to, the better our "natural" healing and development can take hold. Waking up early does give us more chance to "see the light".