Is there a way to create bundled timers?

If the timer is to be used to assist in giving a timed presentation or lecture and I would like to set intermediate counters is this possible with the current version. Lets say I wanted to give a 15 min talk but wanted to be silently reminded at the 10 min mark that that I had 5 more minutes could this be done? I know that could create absolutely defined alarms at 11:45a and 11:50a if the talk started at 11:35a but what if you dont actually start on time.