First of all, CONGRATULATIONS! Second, practice, practice, practice! Go to the physical site of the presentation and just practice. Walk around, familiarity with the site actually helps. Lastly, if they don't know, disclose. For me, I can't hide it. So I have an ice breaker that you may copy and use, it works 100% of the time: "Hello and Good morning" (Hello is my bumper word to get things started) "My name is Pedro Pena and I'll be your presenter for today. Also, I do have a stutter so if I get hung up on any word, just give me 8 hours and hopefully it will come out" (Insert audience laughter here.....it puts your audience at ease because now they know) "If I have a block AND you know what I'm trying to say, Help out Pedro because I believe that TEAMWORK MAKES THE DREAM WORK" (Insert audience applause 👏 here) Now that it's out there, DO YOUR THANG and knock them dead with your AWESOME presentation!! I am a National Trainer for a major medical center and I travel all over the country giving 4 hour PowerPoint presentations to medical professionals (eg., doctors, nurses, etc) in large auditoriums with 50 to 100 participants. YOU GOT THIS! I'm in your corner cheering you on!