Get to the site of the presentation early. Make sure everything relative to your presentation is comfortable. Set up your slides and notes and whatever else you’ll need.
As the guests start arriving, mingle. Introduce yourself. Engage in conversation. This is like stretching before exercising.
Each time someone asks you what you’re going to be talking about, tell them an abbreviated version of the opening. It will make you much more comfortable and confident about the presentation, and you’ll have friendly faces in the audience who will encourage you.