Just a quick update - I'm on BA212 in J this evening 7:20pm (ET) from BOS to LHR and then onto EDI.
I'm sat in the lounge now and everything is looking very promising and on-time. They were able to print boarding passes and bag tags without any issues (including for the connecting flight to EDI... hopefully tomorrow) and don't expect any issues.
They did however ask everybody for the 2 later flights (202 and 214) to leave the check-in and bag drop lines as they wanted to focus purely on the initial departure and didn't want to risk anything going wrong... there were a couple of golds and silvers having a DYKWIA moment but they eventually left and reluctantly agreed to come back later. These 2 later flights are expected to be delayed.
Staff were very helpful and calm - the check-in agent helpfully suggested that we write our names/ addresses etc. on a piece of paper and put it inside our luggage just in case it gets caught up in the chaos - others may want to do this (in addition to bag tags etc.) for some added reassurance.
I appreciate that this won't help those of you in with cancelled flights but I wanted to share to show that things are starting to move. Clearly tomorrow will be the real test and I'm sure that there will be further disruption. Fingers crossed for a better day tomorrow!