LoOu, just taxi in and park (or start a flight from a parked location), then press 'Ctrl/Shift/ E' to shut the engine(s) down and 'L' to turn off the lights. The aircraft will go 'cold and dark.' Then save the flight.
To start up, Just press 'Ctrl/E' - but if you have more than one engine, hold the keys down until all engines are turning. 'L' will turn on the lights.
Of course you can 'do it the hard way' if you like - call up the kneeboard in the aeroplane you're flying - you'll get full start-up and shutdown procedure lists there.
Another thing that you may like to try - years back I found out how to get rid of the 'default flight,' which is just a waste of time. Trouble is, it was so long ago that I forget how! Nowadays, to close down, I just exit from the 'select flight' page by pressing 'Esc' - when I start up again, the game starts from that screen, 'no waiting.'

Sorry, I just can't remember how. Maybe I made another flight the 'default flight' and just cleared the tickmark the next time I shut down?
Try 'escaping' out from the 'save flights' page anyway - set to 'My Saved Flights.' Might work for you.