Camp NaNo Days 1 & 2: Full steam ahead!

So, the July Camp NaNo started yesterday. I did not write yesterday, I was too busy doing other things and basically did not feel like it. I started writing today, around a quarter past eight in the evening, and I just finished at a quarter to eleven on 2,722 words. In NaNo stats, that puts me somewhere between days 4 and 5, if I were going to write this in a proper linear fashion (as if that would ever happen). You could say it was a productive evening (yes, I am in ironic understatement mode, I just wrote 2,700 words in 2.3 hours and I am almost three days ahead of schedule).
As I mentioned, this Camp I will be writing the background stories for some of my characters in my main story. I thought about doing them chronologically, and had actually only mentally prepared for the first character, but then this afternoon I started wondering about the penultimate character, one of the three that has a big reveal/plot twist in her background story, and I decided to just go for it and write her chapter first. It isn't done yet, but so far it contains about 2,700 words of description/exposition and 22 words of dialogue. And that feels fine, this is a character you don't really get to know in the main story, so there has to be a lot of information to make up for that and put her on the same level with the others.
But more amazingly, somehow those 2,722 words were waiting somewhere in the back of my mind just bursting to get out. I hadn't thought about them before, I didn't know which way this story was going to go, I just sat down and wrote. I've experience that before, when I was in the middle of a story and found my flow, but never with a character I knew so little about. Usually I write lots of dialogue on my first days, because dialogue is the easy bit (for me). And then this happened.
I won't have that much writing time in the coming days, so it's good to have built up a bit of a buffer. I wonder whether I will go on to finish this character's story first, or whether I will have another one of these creative outbursts on the other characters. There are eight in total, so I will easily get to 20,000 words just writing those. And then ending up with eight short unfinished bits to tack on to my already written storyline, sounds like a very NaNo way to go about things!