The name of the game for Nanowrimo is commitment. Put yourself in the mindset that writing is your main hobby this month. When you find yourself with extra time, prioritize writing. My tips are steps for you to help reach that goal:

1. Plot ahead what you're going to write that day to avoid the staring-at-a-blank-page-in-terror-itis. We're only 3 days away so not a lot of time to prepare, but this helped me: whenever I ended a day of writing, I wrote a single sentence for what I was going to do in the scene the next day.
2. Join sprints. Peer pressure isn't all bad, it can also motivate you to put a few more words down even when you don't feel like it. If that's still too high stakes for you, just use the timer function on Nanowrimo's website and tell yourself to write for 20 minutes. It's amazing how having a ticking clock can give you a little urgency.
3. Set aside a scheduled time to write. Always write during that time. If you end up with random snatches of time later on lunch breaks or on the bus home or after dinner, use that extra time to write more for sure. But always make your scheduled time.
4. Don't be afraid to jump around. If you know you've got a good showdown or juicy drama or some big image scene coming up, and you're getting bored with where you are or don't know how to get the characters there...fine. Skip ahead. Go write the stuff that interests you.
5. Don't think about what you've already written. If it's good, if it's terrible, if it's nonsensical. Forget it. Making it all hang together, polishing it, filling in plot holes, that's future you work. Present you only care about getting words on the paper.