First two students I ever put up for a checkride (Part 141 safe for solo check) both failed. It was a minor event for both of them, I hadn't taught them the "SOP" method of a failed engine landing (low key, high key) but the results were failures regardless.

As I learned how to be a better instructor my pass rate went through the roof and before long I too was the "give him the problem student" instructor. Only ever had one guy that I finally had to tell him he was just pouring money away.

Don't sweat the pass rate too much this early in your CFI career. Becoming a great instructor is a learning process in itself. As long as you care about your students and aren't just using them as a stepping stone towards your own goals, the results will speak for themselves.

Ricks advice is spot on.