We flew it last January (18 months ago) and from memory it was actually slightly earlier than that - 0840 I think. The flight was fine, old Club World however it’s U.K. daytime all the way so sleeping is quite tricky. The queues for immigration were awful and I think it took about 90 minutes to get through. Made all the more irritating since the Japanese can sail through our eGates but hey Ho.
The only saving grace was that by the time we’d got through and then worked out how to use the JRail network, rush hour had died down and the trains weren’t rammed into town. Obviously we then have the issue of not being able to check into our hotel at that time either which is also annoying.
Personally I prefer arriving in the Far East early evening which means leaving U.K. at that time and I would opt for a later flight every time. And the immigration queue was awful - similar to places like LAX and JFK.