I'll throw in.
1. 14 years
2. First job was at McDonald's at $5.15/hr (NY minimum wage), followed by summer youth employment jobs through my county, highway dept. during college summers, and 4 years of college work study, all at minimum wage, which by then was $7.25.
For a 13 year old kid in 2001, minimum wage was big money. Now, I couldn't get by on minimum wage. I'm a pretty frugal guy - I take the bus for free every day (job perk), drive minimally, eat out probably once every two weeks, and keep my thermostat at 65 unless its below 0. No kids, one dog, one fiance who makes about the same as me, which is to say, not much. If my salary were suddenly cut to minimum wage, I'd be in a pretty tight spot.
What about setting an age limit on minimum wage? One prominent argument for minimum wage is that it does, in fact, provide a tremendous benefit to teenage labor, which is absolutely true, but isn't a living wage once you are living on your own. Why not legislate a higher minimum wage once you reach, say, age 21?