Just don't let the muscles tighten up when you enter the Class. Stay relaxed. At any point if you feel Stress, just take a deep breath. When you're exhaling (make sure to exhale through Mouth) the deep breath, feel you shoulders getting relaxed. I am a stutterer as well. I can really comprehend your feelings. If you feel anxiously nervous before the Class. Let yourself be. Let yourself be nervous. Don't try to force yourself to be perfect - it will make the situation worse. Try to focus on the lips movement on each word and try to stay focused on your concern or topic. You're gonna do the BEST. Believe yourself. Don't force things. Lets yourself be nervous because it's normal.