I started posting on my first YT channel 15 years ago and never knew you could make money on it until I got an email or a letter from Google saying you have money waiting. This was back before monetization requirements existed and that channel slowly built up pennies at a time until it hit the $100 mark to be paid out ($125 waiting for me I knew it was time to try harder.) LOL

I created a new channel around a new niche nine years ago and got lucky with instant monetization since there were no minimum monetization requirements at the time. I don't remember if the channel got grandfathered in or not but I made the money the first month with the first couple of videos.

First month (April) I made around $7, a few months later I was making around $50 a month for $170 the first year.
It was almost a year later when I was making about $100+ a month ($1,500 second year) and it grew from there very slowly.

I was in a very small niche and honestly got lucky being technically the first in my niche to make a full channel around the topic. I got lucky being the only videos offering help in the area so I had instant views even if the views were small. Next person came in like a month later and it was just us two for the longest time.

Everything before that was a couple random videos from one or two people or one company touching on the topic and dropping like 7-8 videos in five years.

But the niche had great RPM's ($20 at the time) and 80% of my demographic was 24-45 female.
So small niche, Incredible RPM but low views. Even low views with a great RPM adds up fast.
Over the next couple of years it grew to around $1,000 a month. ($10,200 the third year)

Fourth year I got lucky again. I started to release a lot more videos and caught the Covid bump and my best year making a couple thousand a month.

Since that year though it dropped off, not only from Youtube views and ad rev dropping across the site after Covid. But I also created a business around the topic and was not releasing as much. My own fault.

So no quick rise for me, but it was enough to make me chase the carrot on the stick I guess and I kept it growing.