Nikki and Rob pretty much nailed it. I bred a 1200g 4-year-old female and a 1700g 18-month-old last season. They both laid healthy clutches and are back up to weight for this season (the smaller girl actually beefed up to 1600g!). Personally, I wouldn't breed a female that is both young and small, simply because I'm not in a big enough rush to risk her health for a couple of eggs.