Note, that the following is NOT a counterthesis to JB's post, since we're talking about "normal" kids, whereas i was already "tainted" in that age; even more than i am now, in fact. :=}

When i was around 6-7 years old, i was terrified by the thought that the girl/s i was attracted to at the time, and had constant fantasies about, would one day grow breasts. I actually talked to adults, and even called a radion program where people called in with medical questions, about whether the growth of breasts can be stopped at a young age. I'll leave the responce of either to your imaginations - it's more fun that way. :=D
Later, however, i became gradually more and more tolerant towards breasts, though i still always prefered them small.
Most of my adult life i saw "pretits" as the ideal, with anything that forms a fold being too much, and anything that can't be distinguished from a boy the same age being too little.