Patrick Morrison on his Jeopardy Experience:
Mastering the buzzer is certainly something that requires considerable effort, and some contestants never really seem to get the hang of it. One must wait until Mr. Trebek has finished reading the question before a set of lights go on, allowing you to ring in. Ringing in too early locks you out for ¼ of a second. The key is to anticipate the moment the question will be finished, because waiting for the visual cue often leads to being beaten out.
If you have ever wondered what it’s like to be on Jeopardy, this seems to cover it all.