I did not have a schedule when I started writing. In the beginning I took the occasional boring evening to write, sometimes listening to music or watching television. Then I started writing an hour or so each lunchtime, sparing fingers from the keys only to grab a bite of sandwich or sip a drink. I produced my first thirty stories (two of which actually sold!) this way before I abandoned writing entirely.
When I did get back to writing about thirteen years later, I set aside a few hours each evening to simply write. Only occasionally did I miss writing for at least an hour. My pattern was the same for years; eat dinner, do family things, walk the dogs, and then write for a couple hours. Because of the time constraints I turned out mostly short stories, although I did manage to struggle through a few novels that could have stood some more serious attention.
I cannot stress the importance of sticking to a schedule for writing. A decent novel contains about a hundred thousand words. That's less than three hundred words a day! If you write a thousand words of crap and edit three quarters of it out you've accomplished your daily quota. Anything more than that is a bonus. Writing regularly also hones your literary voice, making your phrasing and styling more consistent. Another benefit is that it allows you to maintain a steady focus on the story itself, holding everything in mind prevents missteps of timing, characterization, or "fact."
It also improves your typing speed.