well IMO this would be the last time to breed her because if im not mistaken, in captivity its 6-10 years is their lifespan IIRC so you may be adding an unnecessary risk, but me, this would be the last year. As for how young, i would think 1-1.5 years old, but i honestly dont know how off i could be. its not like there is a way to look and say "ok shes ready, have at it guys" other than maybe just the size, but like i said these are my opinion and should not be considered reliable in any respect lol