This scenario is normal. We try to give you a normal sleep overnight and then for delay shifts with an early start, sleep and dark (and melatonin) early in the flight. We are using the sleep to support the melatonin advice. This will make you shift faster.
​
Most people are a little sleep deprived and an extra sleep on the plane will do you good and help you stay up later. So just relax and enjoy some quality time with yourself.