I did something similar for a while but other concerns pushed my routine out of the window, and for the sake of my sanity I shouldn't have kept on with it as long as I did. If I could recommend one thing to anyone thinking of doing an early-morning stint, it would be to keep an escape route clear. Don't commit to more than a week's work at once (you shouldn't be doing this anyway) and make sure that you can unconditionally drop the project at short notice if something comes up. Otherwise you will find that your work strategy is very fragile and very explosive.

That said, the particular issues I faced were external to my early-morning work strategy, and on a level playing field it is a wonderful way to do some of your best work.