We realize that you cannot get a full nights’ sleep before an early flight and so suggest a nap time as long as possible, consistent with your normal sleep time.
If you can go to sleep earlier, and wake closer to the flight, then you should do so but
it is hard to go to sleep earlier than normal unless you are very tired and so it is unlikely you will fall asleep much earlier than normal and
we assume that you need 4 hours before the flight to get up, travel to the airport and check-in, a reasonable assumption for international travel. If you need less time than that, then sleep as long as you can. Unfortunately, the clash between your desired sleep pattern, shifting the clock and the flight times sometimes results in difficult requests. The long-term answer is to avoid early morning flights and either take an overnight flight and sleep, or a daytime flight at a time that permits a full sleep the night before leaving.
That's it! Have a great timeshift!