No one likes to rehearse. Frankly, it is a pain. And with all the work you have put into the presentation, you know the material, so there's no need to worry. Right?
Rehearsal is important to the success of the presentation. Delivery is where the content meets the audience. Essentially, you are taking a two-dimensional presentation of words and pictures and moving it into three dimensions by the addition of yourself. You are adding life to the presentation. In this instance, you are the actor. And, to be blunt about it, actors rehearse.
Before you rehearse, take a good look at the room, starting from the rear. If you stand at the back, you can judge for yourself how large or small you will appear. Keep that in mind. If you plan to reveal something small, make certain that everyone can see it, or else don't show it.
Then go to the stage and take a moment to get familiar with it. Where will you enter? Where will you exit? If you have visuals, where will they be? Then go to the podium; how does it feel? Adjust the microphone to your height. That way you can walk right up and speak. (If you have to adjust it in real time, do it. Don't try to talk without one.)
If time permits, run through your entire presentation, complete with visuals. Practice as much as you can. After your rehearsal, thank the stage crew, if there is one. Your friendly demeanor can do a lot to improve the mood of the crew. Treat the crew members respectfully and they will do wonders for you. Then walk away. If you are happy, get a good night's sleep. Read over your speech in the morning and maybe practice in the mirror. Focus on the outcome and relax. You are ready to stand and deliver.
A note about using a teleprompter. A teleprompter (a term that has come to mean any form of prompting device that projects words in front of the speaker) is an aid that many speakers use. Used well, a teleprompter is a godsend. It helps the speaker look at the audience and still keep his or her place in the text. Used poorly, it can be as restrictive as a straitjacket on a mental patient. There is an art to using a teleprompter, so if you have never used one, practice with it first. If you are unsure about it, decline it unless you have a couple of hours to practice. (If you use a teleprompter, you will need to get your text or notes to the teleprompter operator in advance, preferably in computer form, so that the operator can enter and format it for you.)