Press i to start inspection, after 15 seconds you will hear a buzzer, the buzzer signals the end of inspection time, now put down your cube and hold down the space bar with both hands, once you are ready to start solving release the space bar and the timer will start, once you are done solving, press the space bar again to stop the timer, to restart just press i again and it will start over.
I hope this project helps you if you don't have access to a speed cubing timer and you are tired of having to use your phone or other device's default timer for timing your solves. Have fun!