It's earlier than my daughter, but not out of the ordinary... all girls are different, and it seems to be starting earlier and earlier for some.
I gave my daughter "The Care and Keeping of You" (the entire set which came with a journal and small "personal" bag to keep "personal" items in) for her 10th birthday. She and I regularly discussed the books in the weeks afterward, as she was reading through it. Now, she has fewer questions (she just turned 11), but she is fine asking anything that she thinks of, and the book definitely helps her know WHAT to ask.
She didn't REALLY need a training bra at 10, but over the past 6 months, she has. She received a couple of VERY nice ones as hand-me-downs from a friend from church (she's 3 years older) and so she started wearing them. No discussion, they were in the bag of hand me down clothes, and suddenly they started appearing in the dirty laundry, lol.
So I asked her if she would like a few more so that she wouldn't run out of clean ones. She said yes, and I picked up some really inexpensive ones at Target. Just cotton with a hook/eye back, no padding. They are really just the little cami-bra things. She started wearing them daily.
She just left for camp Sunday, and I noticed that on Saturday, when she was running around the house organizing her packing, that she didn't have one on. How did I know? Because I could TELL.
I made sure to give her some travel panty liners, just on the off chance she started her period at camp! (or in case any of the other girls did, and didn't have anything, and I let her know that if anyone needed anything to share).
Just buy her some. Take her with you if you want, and let her pick out colors/patterns. Some of them have polka dots and things.
Bras isn't a big deal, really.
And I do highly recommend the Care & Keeping book. It presents things in a very open and conversational way for the girls. :)
The book talks about breast buds and development, too.