We can schedule the load test within specified time so that once the specified start time will reach the Jmeter will start performing load and once the time will end it will automatically get stopped.
Its also very simple and we need to do only one change.
Click on the Thread Group and on the Thread Group page there is one option called Scheduler.
Click on the Scheduler check box the page will display like-
Click on Thread Group —> Click on the Scheduler check box
You can specify start time and end time in the same format given above.
So change the start time and save the script. Press Ctrl+r to start the script. Once time will reach it will start process automatically. Once you will start the script and time will not reach you can see the green light is glowing at the top right corner that mean Jmeter is ready and waiting for start time to reach.