Hi
As with all females of any species it completely depends on the individual, some will be unable to breed earlier than others.
I would say that at the ages of yours both would still be able to have babies in terms of age, but there are so many different factors to think about when breeding that age is only a very small part of it.
Obviously there is background, genetics, possible bad traits etc. then there is also the physical and mental health of the animal. Then there is the type, colour, temperament etc.
On top of all of this it also depends on if the female has had a litter before. It is not really recommended to let a female have their first litter after 8 - 9 months old, as some people think that a females hips will fuse if they havent had a litter before then, but i have not found this to be true at all. I have had females give birth to their first litter here who have been over 12 months old with no problems, but as i have mentioned the first thing to to consider is the females condition and health and if she could physically and mentally handle a litter at that age, especially if it would be her first.
Personally i wouldnt breed a female for the first time after around 14 - 15 months unless there was very good reason and the female was in excellent condition.
Tammy x