In the wild they all have to brumate if they live somewhere which gets sufficiently cold, regardless of age.
This year I am brumating my hatchlings from May and June, as well as all my adults, although I do not brumate the hatchlings for as long a period.
The issues to consider are not how old they are, but rather how well-fed and how healthy they are. Never try to brumate a sick or underfed animal.
Skye