If you are asked – or rather told – at the very last moment to present something instead of your boss, it's not entirely your responsibility. It is good to remember that it is primarily the responsibility of the person who gave you virtually no time to prepare. Clearly such a situation will be tough even if the prepared presentation arrives by e-mail immediately after you have learned it is up to you. What to do when you don’t have the opportunity to rehearse and practice the presentation? Here is some advice from presentationmagazine.com.
1) Try to escape
Check whether it is really necessary to deliver the presentation at the given time. Unfortunately, it often really is necessary: simply your boss or colleague cannot attend that day. If, however, it is at all possible, avoid it.
2) Don’t get stressed
As mentioned above, you are not to blame. Yes, your performance might not be outstanding and you may get some flak but at least you know that it's not entirely your failure. The fault lies elsewhere.
3) Do what you can
Go through the presentation, even if only quickly. Once is still better than not at all. It is always better to know what will appear on the next slide before facing your audience. If possible, read the presentation through aloud: you will thus have a clearer idea of what it is all about. If you have a PowerPoint presentation available, remember to go through the notes and run slides in presentation mode since you could discover some additional information. This is not always there but it might be.
4) Do not apologise
Obviously you are not in an ideal situation but do not apologise. At the beginning of your speech briefly convey apologies from the person you are replacing. Explain how this person would have loved to present but unexpected circumstances made it impossible. But do not apologise for not knowing the topic in depth – or at least don’t apologise in advance. Doing so would only undermine your own position.
-jk-