There is never any guarantee, remember that right now she is growing and her metabolism is very different then what it will be in a few months, I have had female growing and breeding at 18 months (they were actually 1800 grams by then) but the majority will breed at 2 years, however I have had many females also not breeding before 3 years of age simply because when they reach 1000 grams they hit a wall, stop feeding and stop growing.

Again there is no guarantee even if she is ready does not mean she will go that season that's why you should not put all your eggs in the same basket and should have more then one female to pair.