Who calls them "oldies"? I prefer to call them "Veterans".
I agree. It's the same as calling a person a "Kid" a "Man" or a "Woman". In the real world, I believe the line is crossed when the person has gained independence from the rest of the family. For independence, it doesn't matter how old you are, it matters on how much you've matured and learned about your surroundings.
For example, I once had an adoptee who was around 26 years old (married) but didn't know diddly squat about the internet (I had to walk her through on how to register for a photobucket account, upload her pictures, and teach her how to place them on
ZU). Though she had the maturity of an adult when she spoke to me, the knowledge of the forums was close to dwindling.
Time isn't the factor, it's knowledge and maturity. She clearly had one, but not the other.
Now when it comes to a "Veteran", time is a factor (along with knowledge and maturity). It's when regular members and mods easily recognize you from your personality (even if you've become inactive for months/years). Veterans usually have been active for years (three years to say the least...that's my opinion).
Really, there are three stages: Newb==>Regular Member==>Veteran (my adoptee evolved into a Veteran!!![/bad pokemon joke])
-BGS