3 years/36"/300grams. I'd say weight is most important, without question. I'm not sure that I'd breed a 300 gram year old snake either, but that's just me.
As far as a yearling, who knows. You've got people like Dean with 140gram snakes that were born in 2005, so when next summer rolls around you'll probably be looking at a 300 gram yearling, or so.
I've got some yearlings from Rich that are 50-60 grams, and I've got some of my own that are less than that. It's all about genetics and food supply.