Generally, the larger rabbits (Flemish Giants, Californians, New Zealands, Palominos, etc.) should be bred the first time around 8-10 months of age. What's too old? I've had trouble getting does over 16 months of age pregnant, and most won't successfully get pregnant after 18 months. Although I did have a Flemish doesuccessfully kindle and raise her first litter at 23 months of age. (THAT was a surprise!)