Once you've entered the necessary Time Based or Calendar Based information, click the Begin button to start the timer.
In order to end a scheduled job, bring the scheduler form up (F8) if it is not already then click the End button.
Once you've started the timer by clicking Begin, you'll note that the toolbar buttons within the application are no longer available except for the Pause button. So long as the timer is running, you should not attempt to use this instance of CPPT for any tasks other than the scheduled task. If you need to use CPPT for other non-scheduled tasks, simply open another instance of the application by running it a second time. As long as the timer is running, your computer must remain on and CPPT must remain running. For convenience you may choose to minimize the running instance of CPPT to a button on your taskbar.
See also:
Running the Scheduler