No I not there. but I've been monitoring LHR departures and no departures or arrivals in T3.
And no signs of opening:
All flights at Heathrow are now operating from Terminals 2 and 5 following the temporary relocation of airlines from Terminals 3 and 4. Rail operations will continue to serve Terminals 2 and 5; but are suspended to Terminal 4.
All about opening it was höpöhöpö.