I also Stutter in front of large group of people, I think it's a kind of social and performance anxiety (you feel anxious when you have to 'perform' in front of large group of people). Nevertheless, I think what kinda works for me is that I have to rehearse every time before my speak, especially the greeting parts, and also just say those greetings as short as possible to save you the trouble (like g'day or just hi instead of: Good morning, everyone). In my experience, overtime when you feel the task become less formal and more business-as-usual, you'll start to feel less dread and speak in a somewhat normal manner... Best wishes!