The 77Gs should be a thing of the past come April. As things stand now:

• In March the three remaining ones will do a total of 77 flights ex-LHR (so 154 if you include the return journey):
  • 16x BA195 LHR-IAH
  • 15x BA281 LHR-LAX
  • 12x BA43 LHR-CPT
  • 7x BA283 LHR-LAX
  • 7x BA297 LHR-ORD
  • 5x BA295 LHR-ORD
  • 5x BA67 LHR-PHL
  • other odds and sods such as IAD, SFO & BOS
• In April, the number will go down to 11 flights, of which 9 on BA295 to ORD

I can't tell which the specific days without going into each single route, apologies. The next 77W to go through refurbishment is due on 31/03, and all will be retrofitted by August (that's the plan; as usual, a bit like it happens when you refurbish your upstairs bathroom, once you "rip it up" you might find unexpected 'treasures' like corrosion or other issues. That might slow things down.