Using the Set Rehearse Timing Feature
By default, PowerPoint is set to advance from one slide to the next when you manually advance the slide. You can change this default setting and program your PowerPoint presentation slides to advance at preset intervals of time. To do this, practice your presentation and save the rehearsed timing.
For example, if you practice your presentation and spend seven seconds on your first slide and four seconds on your second slide, you can then save the rehearsed timing. The next time you display your presentation, slide one will advance after seven seconds and slide two will advance after four seconds.