Random thoughts:
11 is plenty old to have a concept of what it means "to wait". Sure, an 11 year old won't grasp the whole picture: That is, she won't understand that she may experience physical desires and pressure from guys, but she's old enough to understand that the world will "encourage" her in a direction that may not be healthy for her in the long run.
I think it's fairly common for girls in middle school -- late middle school -- to decide what they're going to do/not do as teens. I know that I decided around that age that I'd never touch drugs (and I never did), but I'd drink in moderation only once I reached college (and that's exactly what I did). I made other decisions about sex, morality, college, etc. and stuck to them with about 90% accuracy.
I think a girl who decides "to wait" (whether she wears a ring or not) will at least wait longer than a girl who never sets such a goal for herself, and that is a huge positive. I mean, consider the maturity difference between perhaps 15 and 18. An 18 year old is much more likely to use birth control and is more likely to know what she's getting into.
I don't understand the people who are against "waiting". No bad can come of waiting, while much bad can come of having sex too young /with the wrong person. Disease, unwanted pregnancy, emotional entanglements with which the teen isn't ready to deal.
I told my girls (before they had a first boyfriend) that all girls -- or at least almost all girls -- think that their first real boyfriend is "the one"; that is, that most girls believe they're the lucky one-in-a-million who met her soulmate at a very young age, and that she will never, ever look at another boy for the rest of her life. I told them that many girls "say yes" thinking that they're going to marry that fellow anyway. My oldest is in college now, and she's told me that it played out just that way for most of her friends. She thinks I'm brilliant for having told her ahead of time it'd work that way.
I told my girls that they shouldn't have sex while they're still in high school -- under any circumstances. I pointed out to them that high school is a very small world, and if they broke up with the guy after sleeping with him, they'd essentially be "trapped" with him. They'd still see him in math class, in the hallways, etc. My oldest is quicker to talk to me about such things, and she agreed that she never wanted to be in that situation.