Timing is essential when speaking in public. The clich: It is not what you say but more on how you say it, applies so much to public speaking.
Where you put your pauses during your presentation is one of the important aspects of maintaining an audience that is free from drowsing off. Couple this with humor and you are definitely on a roll.
Timing is the element involved during reactions that are spontaneous especially on developments during your delivery that are unexpectedly expected.
Do not forget, though, that when you expect any laughter to burst any time soon, avoid speaking as your voice and whatever it is that you are saying will most probably be drowned out by the noise of the audience.
Make sure to remember that laughter is extremely difficult to get and so very much easy to discourage. Try as much as possible to maintain eye contact with the audience for a little time longer when you deliver that punch line.
The audience size could also affect the way you use your timing. When the audience is small, the presentation you have will most probably be delivered in a lesser time compared to if you have a large audience. The reaction of...