Well a newbie is not dependent apon posts, my deffinition of a newbie is some body who is still learning the simple stuff that all aquarists should know.
What i think you mean is how do you stop being a tiny winy fish, when you have 100 posts or mor you become a small fish i think 500 is medium fish 100 large fish and1500 super fish moderators are not picked by # of posts and the one and only charter fish is the person who started the website.