I have bred female collared when they are less than one year old before with great success. First of all though, they have to be large enough. The size is based only on my own personal opinion. If they are very large, I'll go ahead and brumate them the first winter.
I don't understand your question. If she is too young to breed, then I'd get her out of the cage with the male...especially if he is trying to mate with her. You may be surprised to find she actually becomes gravid and lays some eggs.