Given you can no longer book F on the 107/106 LHR-DXB rotation my money is on DXB as the launch route (not withstanding the MAD schedules to provide line experience). Try it yourselves. Every 747 has 14 F seats and not a single one for sale in Feb 2020. Now from a selling inventory POV it is no biggy. The inventory will be for A350 and all they have to do is change the equipment code after the ‘big reveal’.