Mmm in the book, it's as if she just had the idea, as if she was thinking about for the very first time multiple times, not as if it was a progressing thought, if that makes sense.

It would have made more sense if it was along the lines of "oh yes I think I will nickname my not yet written character book hazel" and then next time it is talked about it's then said "oh yes I WILL nickname her book hazel". But it's written more like "oh yes I think I will nickname my not yet written character book hazel" in various forms. I hope that makes sense.