Every. Single. Day.
When I wrote Soul Mates (A different kind of love story) I set a 6 am alarm to get writing time in before that other real job thingy. After a week or two I didn't even need an alarm. I just stumbled out of bed, hit the button on the coffee maker and headed for my desk. Everyday until I typed the words "The End."
One thing that did was get the book finished. At least the first draft. But considering the other first drafts I had from other creative endeavors this was a pretty clean first draft. I believe that's because I was more focused on my task. It was time to get to work and that's where I went on time. It also gave a deep satisfaction. Yes, I could finish a book. All it took was a little discipline.
Do you have to get up at 6 am? No.
Do you have to set a time to write? Yes, that gets you to the table where your craft begins.
Stephen King said, in his book On Writing, that he goes to his desk and doesn't get up until he had 10 pages written. Some days he's happily tripping down the road at noon, other day's he's there late until he chokes out those 10 pages. That is discipline and that is why he's such a prolific writer. I highly recommend his book, On Writing, for all writers.
Okay, you've picked a time to write, now what?
Set up your desk so you can get right to work and not have to struggle to find a pen, plug in your laptop, or find your reading glasses. Your writing space should be ready when you are.
Now it doesn't have to be a fancy desk by a beautiful view and your favorite mug. No. It can be a quiet corner in your bedroom, a little nook off the kitchen, or anywhere there's less distractions. King wrote his first book with an old selectric on his knees in a laundry room. Get creative, get a refreshment, and go to work. Okay, you can bring your favorite mug.
So that's it folks. Most important thing a writer needs is a set time to go to work just like any other job. Show up and get to work.
You can do it!