I think if she were 17 (or 18), I would just drop hints. Finally, I'd tell her after she had several sleepless nights. Herherher...
Then again, I posted myself on Exhibition when I was 17, and I didn't see any heads rolling. I got many compliments. Oh, and yes, I was banned. (PS: Everyone who commented on my early posts back in 2003- YOU LOOKED AT KIDDY PORN!!!!!)
PPS: And you know, really, my body hasn't changed all that much from 17 to 19.