Yeah, I think I'd either wait until one of her friends starts maturing or just try to beat the school to the punch. Will the school send a notice before they discuss that? Some do. No one told me a damn thing, and I was 9 when I started. I thought something was wrong was me. My grandma just handed me a pamphlet that she had given my mother in the mid 60s. Not helpful.
Edamame - I already bought my one year old the Daring Book for Girls. I might have to go buy the book you recommended and tuck it away along with that one. By the time she's old enough she's going to have quite the library.