I had heard this also. I think it was only used on the Caribbean routes, I guess BA may have thought they were just offering a scheduled flight to the charter classes and so crammed a few more in but kept the scheduled fares!
Due to customer complaints BA were going to change those aircraft that were not already 3-3-3, to this configuration which is more akin to what other 777 operators use.
CO 3-3-3
DL & MS 2-5-2
I've not been on a 10-wide 777, it must make the aisles real narrow!
As to the timing, who knows now?