The difference between a full shave and a buzz is the infinite forehead vs light hairline. The infinite forehead adds 10 years of age. But, how do I get the photos once I have buzzed?
The definition of NW4 is a NW3 with thinning in the forelock or crown. I can't see any thinning, so you're at most NW3. But, if your hairline still looks almost straight and not wedge-like from the front, then it's NW2. The earliest NW2 would look straight from the front with receded temples that appear at the sides. NW3 appears when there is a clear triangular wedge shape. So you're still a middle-of-the-road NW2. To me, a NW2 is a full head of hair. It's what dreams are made of.