We don't think that there is any wrong thing, its natural process. In common language when bull sees any cow in heat or able to breed only then he started the process, any cow which is not in heat or adult bull never try to breed its natural process no issue at all, if you will observe bull inspect each cow and sniff to start the process. Usually in big farms, farmer used some bulls to inspect ready to breed cows though this process and isolate those cows for injecting of semen of higher breeds.I have a cow that calved 2 weeks ago. I saw my bull mount her yesterday. Is there anything wrong with him mounting her so soon?