I start my day just as if I were going to work. Get up with the alarm, do morning chores, take a shower, dress decently (but not office-nice), sit down and start working.
My first task: send email to someone, preferably a team.
There might be a little web surfing first, but I did that in the office, too.
My work doesn't require set hours. I do it this way simply for the discipline.