Almost 30 yrs. ago (I am 37) a friend of mine who was 8 or 8.5 started wearing a training bra in 3rd grade, and believe me back then no one ate organic foods but most of the girls I know at least started puberty between 8 and 10. I honestly don't think that 3rd grade is too out of the ordinary to start puberty. Like the rest of us girls she got her period in 6th or 7th grade. For me I started in the 4th or 5th grade and got my period the year I turned 12. My sister started at the same time and didn't get hers until she 14. My DD1 is 2 months older than your DD and she hasn't started complaining of pain yet, but it could eventually come this year, but I figure unless it comes on super fast and there is a reason for me to be concerned I figure it is just a part of growing up.