Got a bull bitch that had her first season 3 months ago at 16 months old. Think if your going to breed and want to up the odds of not missing it. Couple of trips to the vet/ fertility get the bitches bloods done. Ok it costs about 30 quid but atoest you know your stacking odds in your favour. I also put her round another bitch in season to try bring her in as I thought it was a little strange she hadn’t had one up to then. Within a few days she came in .