Start the timer of the stop watch and get indicated when the timer finishes.
Click on "Start" to start the time.
Once the timer reaches 0:00, it stops with "ding" sound to indicate finish.
How to Change Timer
Click on "Change"
Edit the value of the Timer as "min:sec"
Now Click on Set to make the change
Now you can click on "Start" to start the Timer.
Credit for "ding" sound mp3 goes to
http://www.freesfx.co.uk