Follow on 
I can’t emphasize this enough! Do not wait to start coaching until you think you know how to do it “just right.” Trust the coaching process. Your early attempts at coaching will surprise you in their effectiveness. As successful business leaders your inclination will be to avoid being an unskilled novice. Fight that inclination! The only road to mastery is through the rocky roads of new skill building. Every coaching interaction will be building your experience, competence and confidence.
Considering hiring a coach to “coach the coach.” That’s me! Set up structures within your company so that you can have others be a second set of eyes and ears for you regarding how your coaching conversations went. Make some notes, practice being a detached observer, and you will get a sense of how you did in coaching.
In coaching school, we do three-way coaching. So you could even have a colleague sit in while you are coaching, or you could have a peer or even a teammate give you feedback about your coaching. The bottom line is, the only way you are going to become an effective coaching leader is to practice.