Can't remember, probably 8 or 9. But I do remember I didn't get eyeglasses until I was about 10, even though I've been near-sighted / legally blind my whole life. I also remember punching the crossing guard lady in the stomach when I was around 7, and then trying to make a run for it, I didn't get far (icy sidewalks
We were all free-range back then. Fathers and mothers worked hard in factories and kids had to take care of themselves. There wasn't as much traffic in those days and needless to say, drivers were not distracted by cellphones.
When I was about 12 I rode my Schwinn Sting-ray 5-speed bicycle, by myself, from Franklin Park to the Brookfield Zoo (all near Chicago) using some forest paths along the Des Plaines River.
When we moved to Miami soon after, my brother, sister and I were left on our own because our mother was disabled by an accident and our father stayed in Chicago to keep working in the International Harvester factory until he retired. My sister and our mother lived with our grandma and me and my brother lived in a apartment of my grandfather's house. But our grandpa didn't really take care of us, we were pretty much on our own and we walked to Winn-Dixie and did our own groceries.
School in Miami soon bored me so a school counselor suggested I take some college courses. So I started college when I was 14, dropped out of high school at 15, took a GED test at 16 and graduated from college at 18 with a degree in computer programming. Back then we used punched cards to program the mainframe, an IBM System/370, however I did get to use the DEC PDP/11 terminals to program interactively in BASIC class.
Before I was 19 I scored a programming job with the grandson of the founder of the college I just graduated from. At first we only had an Apple II Plus but IBM PC's soon emerged and I programmed those in BASIC for capital budgets and programmed Lotus 123 spreadsheets including pie charts and bar graphs.