I'd say, on a large male, mature weight of 75, not particularly lean, between 5-10 lbs from age 10 months. Depends on your lines. Xanny was pretty much done by 1, had her first heat at 7 months, a very quick maturing female. I remember hearing a UKC judge comment that there were young males they put up (between 10-14 months) that they regretted putting up, because when mature, they were quite overdone. Liking lean dogs w/some leg myself, I see plenty of males I like until I find out they're only 10 months, and not done filling. Some apbt lines are very slow to mature.