Before you begin, tell them that you stutter. You dont have to make a big deal out of it, just something like "Some of you might already know this, but I have a stutter. So, please bare with me if I trip up" and then launch into it. In some ways, it's good to go early. That way, there won't be heaps of fear as it gets closer and closer to your turn. You'll be able to sit back and watch the others. Best of luck.