Help me not bomb this

Help me not bomb this Hey friends, I give a speech in from of 400 people next week. I only occasionally stutter, but when I do, I sometimes can't pronounce another word. What would be my best bet, XANAX or Proponalol (a beta blocker) ? I've read that Xanax can make you sleepy, but that Proponalol can actually CAUSE stuttering, so I'm not sure what to do now.