When you decide or find out how long you are going to speak, time yourself during rehearsals and cut out the unnecessary bits that make you overrun. A common mistake is to read the script while you time yourself. You usually read a different speed from when you talk. Instead of just reading, deliver your presentation as if you have an audience, including all the pauses and with your normal speed of talking. Make sure you finish a minute or so before the allocated time as you tend to be slower sometimes under real conditions.
Here are some suggestions to help you stick to your schedule and use your time effectively:
1) During the presentation, put a watch – preferable with digital display – somewhere you can see it. Look at it from time to time to see how long you have left and control your speed accordingly, without letting your audience notice because it can be rather irritating
2) Choose a paragraph from a book, read it with your normal talking speed and time yourself. Repeat this same procedure for longer paragraphs and try to guess the length of time you have been speaking for. Doing this several times will help you find out how long it takes you to say a given number of words
3) Another method is to make your script fit the time and then roughly memorize your words. This will enable you to stop exactly on time without having to worry about it.
4) If your visual aids require some time to switch from one slide to another, try to include them in your rehearsals. If they are not available at the time of preparation, take them into account and allow another minute or so for changing slides.
5) Present on your own several times and time yourself. Adjust the speed of your talk each time to make it fit comfortably within the given time. If it doesn’t, go back to the drawing board and take out a few sentences or ideas.