For a Freelancer? Everyone in the canon appears to be at least in their mid- to late 20s, if not older. I know one player here-- I want to say Nevada?-- is 21, and I'd like to keep that as the absolute lowest. At 21 you would have very little experience under your belt (even assuming you joined at 18), and the freelancers overall are meant to be skilled/experienced in their fields. Those who are younger will (generally, there could be exceptions) be less skilled than their older counterparts. That choice, however, is up to those of you making characters.