How many daily users do I need before I can monetise with ads?

Hi IH's,

I'm currently in the early days of my side project - agileexamples.io

I don't intend to rule the world with this project. My goal is to basically drive enough traffic to my site to draw a regular £200/month income from ad revenue. Problem is, I'm not sure if that is even feasible due to my relatively small target market. I know there are many factors at play, but how many consistent daily users would I need in order to achieve my goal?

If anyone could share their own numbers that would also be insightful!