Age of websites doesn't really matter. If you consider things like domain name changes, domain hijacks, etc., you'll realize it's really extremely difficult to tell how old a site really is. And editors don't try.
You know your site is five years old. Nobody else does.
Fortunately, nobody else _cares_. A site doesn't automatically get more important as it ages anyway. And if it did, I'm sure there are many sites older than that, which haven't been reviewed yet (not that we could necessarily find them, or recognize them when we did.)
All that matters is how much unique information is contained on a site, and how authoritative its source is--at the moment of review.