Holding a full rehearsal of your speech will give you a good idea if you are taking too many pauses or using your hands too much for the time that is given to you to speak.
Another effective way to time your speech is by counting the words you have used. The thumb rule for measurement is 120 to 150 words in a minute. In this process you have to place a mark after each set of 150 words and then simply count the marks.
If marking turns you off, then you can always record your speech. However, speak with the same pace that you would when delivering it in front an audience in order to time it accurately. For your convenience, recordings are automatically timed. You can make required adjustments in the written speech according to the time you recorded. If necessary, exclude or add words to increase or decrease the length of your speech.
Recording a simulation will also be very helpful as you can adjust your gestures in order to wrap-up your speech within the allotted time. You do not necessarily have to exclude stuff from the speech, as with proper timing you can actually speak and give the same gestures without exceeding the time.