Dragons and their human form.

[Qintopon]

At what age category should a dragon have a human form?

[TuggyNE]

In Core, young bronze dragons and wyrmling gold/silver have the ability to take humanoid forms. So any time after that? Presumably they should pick up a human form fairly soon after they get that ability, as long as they're in an area with a fair number of humans (i.e., most places).

Outside of Core it's probably much the same, but I don't know for sure.

[Seharvepernfan]

At what age category should a dragon have a human form?

Most dragons can only do it via spells.

[Coidzor]

Or an Eberron feat which requires Sorcerer level 5 and being a True Dragon. IIRC that translates into casting as a 5th level sorcerer or higher.