I took BA 117 (LHR-JFK) on 20 April and BA 176 (JFK-LHR) on 24 April and both had the old entertainment system in WT (BA 176 was on a 777, though a 747 is more commonly used on this flight).
BA 113 (LHR-JFK) on 5 June had the new entertainment system in WT (it was a 747, though a 777 is more commonly used on this flight).