Cross-validated is a good site to sharpen one's skills in statistics. Lots of teachers and learners switching roles constantly, almost like taking a seminar. Today, someone said he is just a newbie and he is glad to get my help and attention, and yesterday a guru told me (I'm paraphrasing), "Well when I was a newbie (like you), I had people throw rocks at me too." So, it seems there are layers of newbieness. So maybe this is a question for the "great ones" on the site, "When did it occur to you that you weren't a newbie anymore, and how did you know that?"
I'm interpreting your question to mean "statistical newbie" rather than "Stack Exchange newbie" or "Cross Validated newbie". (If you're asking about the latter two, you advance pretty quickly. Just seeing what other say, comments, closed questions, etc, brings you up to speed fairly fast in most conventions of this site. Most...)
I feel like I've moved beyond statistics newbie, but that's due to lots of reading, lots of Cross Validated, and three years of on-the-job working, above and beyond my schooling. Beyond "not still a newbie", however, I still look at answers by gung, Macro, whuber, to list a few off the top of my head (but missing many great people -- sorry!) and feel inadequate. How do those guys know all of that stuff so seemingly intuitively? I'm not a newbie, I think I'm beyond a novice, but I'm a long ways from that expert level. What's the in-between? Journeyman?
But I can still answer questions. (Especially those with a more Computer Science/AI flavor, where by background is. And yes, I'll admit I'm a bad person who will answer R-specific questions whereas technically an R-specific question is off-topic. Maybe it's because I feel stronger in that area, so can give a better answer.)
You are no longer a newbie when you get insider jokes without having them explained to you. However, you never feel like you are not a newbie because the very next question will intimidate you enough that you will begin to doubt your own abilities. A negative vote for humor? Gee, and I was being frank too-Thanks-that does put some perspective to it.