You need to be there earlier than that,from around 1945 ish the freighters normally start to go out-the B767 Star Air for UPS is usually very punctual around 2000,then TNT,DHL etc.
Looks like 07 going to be in use,so Killead area should be good for takeoff shots,although you don`t get a lot of warning,and pics will be backlit at first.
Still well worth a look,on a nice evening.