I really do not know the average age and number of training years, it takes a guy, all I have are my personal exp.
I started working out at age 17, I did not use any PED's until age 29. Looking back I think I hit my limit at 24 to 26
If I recall right, from other much more informed cats then I, I think the age to start juice, is 25
with at least 5 years of serious training & diet. About the age of 34 I meet and lifted with two other powerlifters/bodybuilders
The one guy told me he started AAS at 15, he was 5'-2" tall. All his brothers were over 6' tall and had never juiced.
I do not know if AAS had anything to do with his height or it was just his DNA.
The 2nd guy started AAS at 20. He said he only did one cycle. Which lasted 28 straight years with no time off, or blood tests. He was stronger, bigger, and workout like monster, and
he had more heart then any one I have ever meet. He won lots of powerlifting & tough man events. Sadly at age 48 he fell over dead at his home on the tread mill. His son found him. It was ruled
a massive heart attack