To reiterate what's been said - your call.

Remember, NaNo is NOT write a 50k word novel in November, it is write 50k words OF a novel. If you start November at 23456 words, then you need to have your story at 73456 words by November 30.

As a pantser, though, I am itching to start because my idea is there. But I have a goal of 80k words in the month, so I am waiting. I did 100k last year, but this is YA so the word count needs to be lower.