I've done it multiple times and it can help in some cases but it can also make it worse depending on your mood that day, the situation you're in and other things that influence your stutter. For me, it can help in situations where I'm usually not that comfortable when these are not that stressful. When it is tougher situations where is usually stutter a lot more, it can have reverse effects and make my stutter even worse. It is different for everyone and affects everyone differently depending on their kind of stutter. I would definitely try it out first before doing it at that big event to see how you respond to it. Goodluck :)