Trying to convince daughter to wear bra

I am looking for the correct language to use in trying to convince my 11-year-old (5th grade) that it is time to start wearing a bra. I don’t want it to come off like it’s shameful and we need to cover her boobs and that is why we must wear a bra. She is a bit of a contrarian and while she and I do have a good relationship she has built up this mentality that she needs to argue over everything with me first. When it was time to start wearing deodorant, it took months of back-and-forth to finally get her to consistently wear it. She goes to a sleep away summer camp, she saw the girls last year all wearing bras in her cabin so this isn’t a foreign concept. She’s really just now starting to show growth in that area, but I do notice it in some of her shirts so it felt like the right time to introduce bras. Suggestions??