No, I think my dd is late. Most of her friends had pubic hair before they left primary school, according to her.
I'm probably more slapdash than most as am very blonde -- dark hair is more noticeable, I guess. Dd1 did have very hairy legs, and had raised the issue of being teased herself, when she was 9 or 10. I spelled out the options for her, tho' I did say at that time I'd rather she didn't start shaving her legs, but if she really wanted to, then she should let me know rather than try any DIY on them. A year or so later she asked more seriously to do something about it, and I got her a razor (tho' she's also tried immac and wax strips).
Personally I would mention to your dd the fact that you've noticed her hair is growing, try to see how she feels about it. You can then comment, neutrally, that lots of women do remove their underarm hair because they don't like the way it looks, and ask her to approach you if she wants help or advice on what to do. I think that's a more neutral approach than the "OMG, you've got underarm hair, quick, here's a razor" approach (not suggesting you would do that, obviously).
It is tricky to get a balance between helping them fit in and making them feel bad about themselves -- I think the fairest thing is to talk about it casually, and make sure she knows what her choices are.