I just spent a few hours messing with this because I was irritated it didn't work. I was excited about the Mavericks calendar feature that calculates travel time and alerts you when you need to leave. However, it kept calculating from my work address by default, and I couldn't see a way to change it.
To fix this, you have to change your "Day starts at" preferences in Calendars, and since Apple doesn't think anyone's day starts at 7pm you have to start and end it at the same time, like so:
Now click an event's inspector and fill in the location, then click the time and under travel time there'll be a dropdown menu for travel time. It should now calculate from home.