I breed when they are 80lbs or more, they normally hit that weight before the age I breed them at though, 7-8 months. But it is really important to breed by weight, but also do not breed them before they are 7-8 months either.
we breed 9 months and at least 90 lbs, If they are not that age and size by October/November to be bred to kid March/April, then we skip htem and wait until next breeding season, which would be the following August for us. Often we will have 2 or 3 we will breed and a couple that are too young/too small. Our main herd is Bred to kid January/February. Then if someone is missed we will put them with the yearlings and kid them March/April. We pull all bucks out from the does so no one kids later than May 1st.