Unless you are traveling first class, take notice to go to the bathroom before boarding the plane. We always do that by being aware when the airline personnel would announce that it is time for boarding, we would rush to the nearest toilet and do our thing. Why so? There is always a queue in the plane's rest room and it is very inconvenient. Besides, I usually sleep when the plane takes off so I don't want any interruption especially from my bladder. For a convenient flight, empty your bladder before boarding.