Well, that depends on how old the AMG was when s/he started medical school, because that varies a lot. At the start of med school, my classmates ranged in age from 19 to 44. So at the start of residency four years later, we were anywhere from 23 to 48.
If you consider a "traditional" student who graduates from high school at 18, completes undergraduate work in four years and goes straight to medical school at age 22, then residency starts at age 26. But lots and lots of people have a year or more between college and med school, or they take more or less time to complete undergrad, or they take a year during med school to do research, etc. etc. etc. ..... so you see, it isn't uniform at all.