I've never done it, but I know the vet can help you postpone season, they do it from time to time here because so few bitches are spayed and no-one wants to have the hunting season ruined
I would set up an appointment to discuss this with your vet. From what I understand one side effect is an increased risk of pyometra since the medicine is basicly hormones. I don't know how significant this increased risk is though. But for bitches that are not going to be bred maybe a spay is a valid alternative? The vet can probably help you evaluate the risks and benefits so you get the best solution for you and Eze