Does anyone have experience with taking a benzodiazepine?

I get really bad anxiety when I have to do class presentations. I have considered taking a benzo like a Klonopin or Xanax. Would taking one of these relieve my anxiety symptoms for my presentation? I want something fast that works quick enough and does not last as long, just for a few hours in the day.

Has anyone ever taken a benzo before an event in which to relief anxiety? Has it worked for you? What does it do for you, are you able to relax and focus better?