Fake confidence can turn into real confidence, if you succeed at this at the start on the presentation you have pretty much nailed the rest(it's a bit of a gamble but is great when it works) Also try to keep cafeïne and dopamine low in the days leading up to the presentation, doesn't work for everyone but if it does it can work wonders, the only thing that physically differs stutterers from non-stutterers is that the amount of dopamine we have is multiple times higher than people who don't stutter.