This realization helped me a lot. In the situation you are describing you are giving someone the power to make you stutter. It can be an authority figure, someone you want to impress, someone you just met, basically anyone. Ask yourself why should they have the power to make you stutter? What gives them that right? If you were reading aloud in a room fluently and they suddenly popped out of the closet or something would you immediately begin stuttering? Why? Take your power back. Don’t give it to others. You have the power to speak fluently. I used positive affirmations, reading aloud to myself obsessively, and intentionally stuttering to overcome this.