My timer is incorporated in my radio, which is a JR378. I set the timer for 12 minutes and it counts down, when it reaches the last 30 seconds it starts to beep , ending in a long beep at the 12 minute mark. It is then i go into circuit and land with a small reserve of fuel in case i need to do a go around. I also record all my flights in a log book, time , weather conditions wind etc.
Bill