In my experience, a starter rock from the LFS MIGHT help a little bit. But mostly, it’s got to go through a few phases like getting a bio-film etc before it will grow. Your tank also has to stabilize a bit in terms of parameters, etc. once that happens, within a few months you should start to get it tho. Keep in mind that it will need calcium and alk to grow and once it starts to do so it can easily suck it out of the water column quickly, depleting and outcompeting your corals even. If you see someone with deep rich purple covering their rocks they are more than likely dosing 2 part to keep it up. So, always understand that there are 2nd and third order effects to everything we want in this hobby. A stable tank is a must before anything else. Good luck!