You should base a full charge on when the charger stops and says it's full...
It's unlikely a battery would ever take it's rated mAH back in during a charge. If it did, it was probably way over-discharged prior to then...
But yeah, ALL lipo chargers will stop automatically when the battery is full. If you watch the screen it's usually when the voltage is peaked at 4.2v/cell and the charge current drops below 100mA.