I don't mean to burst any bubbles here, but taking on a commercial student as a fresh instructor I found to be a daunting task. When I was about 25 hours into my dual given I got my first commercial student. I don't feel I was able to give nearly the insight he deserved.
There are little things that you catch pilots do as you begin to teach that you never thought about. The number of things you catch is literally never ending. They say you will learn more in your first 50 hours of instruction than in your entire training up to that point, I feel that is fairly accurate.
My advice, while it would stink, is to start with private students first. Build at least 100 hours teaching them and then another 100 on instruments before trying to tackle a commercial student. Not to say you cannot do it, but can you do it as well as the average 500+ hour instructor when you are fresh out of the gate? I would suspect not.
If you choose to take the student 400A made some great suggestions. What I would add to that, given your situation, is find out how schools in your area do evaluation flights. If you have to call up some local flight schools, or colleges if you know any, and ask them about what they look for in evaluation flights and why. Quizzing the JC community on this topic may also prove beneficial.
The second thing I would like to mention is ground rules. Come up with your exact expectations for the student to achieve the sign off. Here were mine:
Flight: You must complete every commercial maneuver to PTS with a maximum of one do over in one single flight (may take up to 1.5 hours).
Ground: You must answer my questions to 80 percent accuracy on a two hour oral exam.
I told that to my commercial student day one. I am a firm believer of letting the student know your precise expectations of them for each milestone. For private students, day one I tell them the solo expectations: You have 4 attempts to make 3 safe landings and I will sign you off. Coming up with your personal requirements for each phase of each certificate and letting the student know them gives the student a goal and ensures they know your expectations.
Good luck.