Looking at the heavily photoshopped pictures these days, when I go to the shops my expectation would be that the girls are quite young but when I actually see the girl, some of them are way too older than I expected. I have walked out of the shops in this kind of situation many times thinking that I have just wasted my time. Some of the shops I never went back.
It does not have to be exact age. 2-3 years up and down should be fine imo. Having the age on the description would help lot of us on what to expect when we get to shop. But it's entirely up to you.