From the NaNoWriMo website:
Every year, several people write 50,000 words in three days and win.
Every year, hundreds of people write 25,000 words in three days and win.
Every year, thousands of people write 15,000 words in three days and win.
If you're still writing, you're still on track.
You can do it.
According to Chris Baty, I'm on track. I'm also among thousands of people.