Mnay breeders like the 3-3-3 rule, but sometimes, if a female has reached and surpassed the 300 gram and 3 ft mark in her second year, she is bred a bit early. And then, some females will never quite be a large snake and may not make the 300 gram mark well into their 4th year, but iuf their condition is otherwise excellent, will be bred then. It all depends upon the snake. And males can safely be bred younger and smaller (18 months and 100+ grams).