As I recall, I have my timer set to four minutes on my Widgeon, flying on a 3S 2200 mAh battery. I typically back off the throttle after take-off, and the time leaves me enough time for a go-around or two (three?) if needed.
Our flying field is at about 2000' (610 meters) altitude, and I always prefer landing with a reasonable margin of power in the battery so that, when the timer goes off, I'm not in urgent need to land RIGHT NOW.
Here's one of the latest videos I posted from the Widgeon. The keychain camera records the time in the lower corner, so it's easy to see the interval between take-off and touch-down.