Most " Dollar stores" sell small count down timers for about a dollar that you can use. Most of my students Velcro them on the TX.

Also in agreement with above, I fly 10 min. and don't let my students fly more then that while training. As far as how long you can fly, fill it up and take it up and fly till you get tired or it runs out, just be sure and keep it in a good place for a dead stick. ENJOY !!! RED