Being a noob myself, I can't give you a hard number at which I will no longer consider myself a noob. But I can relate it back to other areas of my life where I made that transition. I don't think it can be equated to dives or years, but a "gut feeling." I will no longer consider myself a noob when I can do the fundamental skills with having to "think" about it (bouyancy control, ascent, descent, safety stops, etc)...A lot of this depends on how often I get to dive. If I can dive everyday for the next 3 months, I will get there in fewer dives than if I make the same number of dives over the next 10 years.
Definitely a good question...