What is the right age to breed my mare horse?

I have a three year old mare that i really want to be bred with a stallion that will be getting gelded in June. He is absolutly AMAZING and i want to breed her before he gets gelded, but i dont want to do it too soon, or if it will be a danger to my mare. I have heard different opinions, but i would really like to know what you all think!!! Thanks so much~!!