This is a question that can be answered best by the breeder of the Queen. Each breeder will know her Queen, including the number and strength of her heat cycles, the risk of pyometra in her lines, her age, weight and overall health. Certainly, There are some who would say not to breed a cat before her 1 year birthday, some say 18 months old, some even say 2 years old When it comes down to it, you have to look out for the best interest of your Queen. Learn about the reproductive cycle so that you can make the best decisions. Lesson 6 in the Course will explain everything that you’re looking for.