How many B2B clients did you have before you needed to hire support?

I know this is very subjective so maybe I'm asking how I can measure it somehow.

I currently have 12 clients. I have spoken with them for maybe 30-60 minutes a month addressing changes to their account, adding new people, tech questions... these clients are 2-3 months old (so relatively new).

So, 45 minutes * 12 = 9 hrs

Right now, I'm either faced with raising prices or hoping that I can handle 50 clients on my own.

Any advice?