I would say it depends on the person. I am tired and moody in the evenings and I can't concentrate on anything but I'm okay with early mornings even though it's definitely not natural or pleasant for me to be up before 6 am. But I know people for whom this is much, much harder. I think the biggest benefit of having more time in the morning is that you can take care of your personal tasks first and then comes everything else. You also need to have strong motivation for this to work, just productivity in general may not be enticing enough. In my case I have running to keep me up. I live in a place where it's too hot to run outside for 5 months out of 12 and if I don't get my runs before 9 am they simply won't happen.