The problem with going by number of seasons is that the variation in when they have a second season is huge. A bitch can have a first season at 6 months, so a second season at a year. IMO breeding at a year old is too young for ANY breed. My own bitch didn't have her first season till 11 months - she has just had her second at 17 months, which is still too young for my breed, but may not be for others, so relying on seasons is fraught. I personally would not consider breeding until the bitch is mature, both physically as well as mentally. Not only will she be in a better position to cope with the effort of whelping and raising a litter, but as the owner you are in a better position to judge whether she is breeding material, and what sort of stud to choose to compliment her.