What I mean is, the host or event organiser can turn the timer on when a presentation starts. For instance, an event's agenda has 6 presentations and every presentation length is 15 minutes each, the host introduce the first speaker and turn on the timer, which will be shown on everyones screen as a green light and the time the speaker has left. By the end of the presentation the light can goes yellow and red, giving the speaker an awareness that the presentation time is finishing.

The purpose of this feature is not delay presentations and keep everything on track. I hope it make sense