Through trial and error I've figured out what times of the day I'm 'switched on' - for example, I'm not a morning person so I leave all the mindless stuff for mornings (answering emails etc).

My best time of day to code is around 2pm - 9pm actually, I find I get more done during those times. I find that I read better later in the evenings and that I'm more of a cheerful person from late mornings to early afternoon - which is when I do most of my phonecalls.