How Being A Yoga Instructor Works?

I've had Spa Day for a while now and just recently got into trying to make my sim a professional yoga instructor. I've gotten her to lvl 10 yoga skill and promoted the class online every day that she's been doing it. My question is if I keep it up will she eventually become super popular where just starting a yoga class will attract a lot of sims to spawn from nowhere and join without me needing to manually click on them and invite them? Also, does promoting the class online actually do anything? Because it seems to not affect anything in any way that I can tell but i'm wondering if i'm just missing something.