Start? It's like cancer. You never know when it "starts." But when did I notice it? Around the time I turned 30. I touched my head, and there it was. Scalp. No buffer zone of once-curly hair. Just a flat, sparsely covered patch of scalp.
24. I passed my hand over my hair just to find 10-15 hairs in my palm. I had nightmares during that time. Imagine being an 5'3 autist manlet, an on top of that, balding. I had serious depression from 24 to 29 when I just became too numb to care anymore.