How much J2EE experience is enough?

[ffew wafew]

At what point can a developer be trusted to lead the development of a enterprise system for a small-to-medium sized business, as a system analyst and architect? For example, how many years of experience and of what type, what type of certification and educational level should be present?

Thanks,
Eric

[ffew wafew]

I mean J2EE-based development of course.