While some mothers kept their sons in dresses well beyond their 5th birthday, most boys were breched by 6 years of age. One alternative for a mother that did not believe her little darling was quite ready for pants, could choose to dress him in kilts . Since Queen Victoria popularized the kilt by dressing her s ons in them, mothers without Scottish ancestry could also choose kilts and kilt suits for their sons. Many mothers used the kilt as a transition to more boyish kneepants suits. This proved increasingly popular and by the end of the decade many little boys were wearing kilt suits rather than more girlish dresses.
Some period movies depict boys in long hair and dresses.
Movies of course can vary greatly in historical accuracy. It is likely, however, that those who have gone to the trouble of depicting boys in dresses and long hair, probably ercised considerable attention to detail.