5k training plan workout

I'm new to garmin and currently doing the 5k training plan,  after I do the warm up phase, it then shows "Run until lap press" with the option to select lap press. Once this lap press is selected it then goes into the additional steps i.e run for 30sec/walk for 30sec. My question is should I stay running after the warm up without pressing the lap press button or does it automatically change over to the next step of the training plan after a set distance is covered or a step time period. This seems to have me a bit confused. Thanks for your help