Wizz S18
Im surprised Wizz hasn't decided to use some of their 5.30-6am slots they have used previous summers for those later departures after 7am, when previously night stopping at the airport...
For Wizz a 7.20am departure is pretty late for them, as they get nearly all their fleet in the air at other bases before 6.30am local times, which would be, 5.30am UK time.
Many Wizz flights will be arriving from Eastern Europe into Luton, before the first departure of the 7.20am flight.