Prior to arriving at the location, do some facial exercises. As you know, the mouth is a muscle that must be exercised to work properly. When you wake up in the morning, you just don't jump out of bed, ready for the day. It takes a few minutes for you to stretch and rub you arms and turn your neck a few times, and then you are ready to stand up. Well, your mouth also needs to be stretched and rubbed so it will work properly when you are ready to speak. Professional singers and speakers do exercises prior to a performance, and so should you. While driving in your car, begin to stretch you jaw and lips. Start to say A, E, I, O, U in an exaggerated way so that you stretch the muscles of your mouth. Also, use exercise phrases like, "how now brown cow," which will help to loosen the muscles in your mouth and awaken your vocal cords. People may look at you in a funny way while you're driving, but just smile, keep up your exercises, and let them wonder what it is that you're doing.
Since we are performing this mock oral as if it were the real thing, there are several things to consider prior to entering the room:
You probably have a knot in your stomach. Well, this knot helps to place you in a more competitive environment. What I mean by this is that it makes you ready for the process to begin. It gives you an edge and makes you sharp. The knot I'm discussing is a slight tightness in your stomach, not a pain that has you on the ground moaning or causes dizziness or fainting spells. You don't want to place that much pressure on yourself, because if you were in that much pain you would probably be in the emergency room prior to the beginning of your testing process. I always had a knot in my stomach prior to any testing process, speech, or presentation that I made. I found that the knot in my stomach helped me give the best performance that I had in me. I also realized, as you will, that once the process began, the knot would disappear because I felt prepared and in control of the situation.
Something else to consider is that you are very nervous and your gastric juices are flowing. Your breath may become somewhat harsh, so I would suggest that you carry a breath mint and use it just prior to your interview. Be sure it has completely dissolved before entering the room or remove it from your mouth. It is the same for gum--don't chew it during the interview. I suggest you don't chew it at all on "game day," because you may forget about it and walk into the room chewing without even realizing it. You will look like a cow grazing in a field, and the moment you realize that you forgot to remove it from your mouth, you will lose your concentration and your and your presentation will suffer.