You'll want to weed out any spelling errors and find other goofs and gaps before you present. Go to the Review tab on the Ribbon to run a spelling check. That's also where others can go to add comments as they review your slides.

On the
Review tab, in the
Proofing group, click
Spelling, and make selections as the spelling checker moves through your slides.

You might also want to have others review the presentation and make comments before you present. You'll find the
New Comment command in the
Comments group, also on the
Review tab. A person adding comments just clicks the command and types the comment, slide by slide. When you review the comments, you use
Previous and
Next, in the
Comments group, to navigate through them.
If you do have others review the presentation, PowerPoint helps the process by automatically attaching the presentation to an e-mail message. In the practice session, you'll see how to do that.