Breed her when she has her 1st natural heat....... a bull most definitely would.
If you want to try and move her up day wean her calf for a few days @ about 30 to 35 days old, this will usually make a cow in good shape come into heat.
If you want to try and move her up day wean her calf for a few days @ about 30 to 35 days old, this will usually make a cow in good shape come into heat.