SnowSnake,
IMHO females can be housed with males as young as one year of age, provided they are in breeding condition (good fat stores, mature body condition - if they look like babies still, keep them apart a while longer). 1.5 years of age is a better bet in most cases (if you are even willing to let her go into her second year that is great). Males it isn't as important. They can produce viable sperm earlier than a year, and even though they are still maturing, are still able to successfully breed with no subsequent problems