I have sold 2 businesses, had over a dozen failures and had dozens of successes ranging in scale from almost nothing a month to more than is polite to share .
The reason I know the years below is because I got into a conversation about this a few days ago with one of my parents.
5 Years Old - First Job working for a family member, I was taught about money early on and always had to work for it. "I recommend every parent do this at a young age because it set me straight with how money works at an early age".
6 Years Old - Sold wood homeade airplanes for $0.06, no one would buy them
7 Years Old - Chalk Driveway Paintings - made $10 in one hour
8 Years Old - Lemonade Stands around the neighborhood
9 Years Old - Recycling Soda Cans - made around $30 per month
11 Years Old - Garage Sales, I rounded up items that were thrown out and given away by people who were moving as well as donations from friends. Made around $500 per month.
11 Years Old - Started my eBay & Dropshipping career which lasted from 2001-2008. I also started a web design firm the same year while I learned how to build my own ecommerce stores. I had a few businesses that became powerseller status before the age of 15.
18 Years Old - Started my first SMB service company
23 Years Old "Today" - I own a fast growing holding company and getting involved with investments such as PE, LBOs, VC & Real Estate.