Originally Posted by
corporate-wage-slave
OK, so until about 2 years ago, check-in desks did not open until 05:00, but you could sometimes get the self service desks working slightly before that. Then there were a number of Fridays where it proved difficult to get all passengers and their bags on to the early BCN service. So yes, BA opens check-in desks - or at least the self service desks - around 04:10, but you won't get through security until 04:30 (and often a few minutes after that), and it is 05:00 for the First Wing Security. For First Wing check-in I would expect them to be fully open around 04:45. If HBO then it's not much of an issue, but for an 06:05 departure the OP probably does want to be in T5 around 04:45 on Mondays, Thursdays and Fridays, not quite so early on other days.
IIRC when I was still at BA, the initial move to 0400 check-in on peak days may have been back in summer 2019. At first, it was BA agents labelling bags, collecting them and then when the baggage system opened, they were sent down the out of gauge belt, think it was south. It took some discussion to get Heathrow to agree to open baggage system and security earlier.
The earlier shift starts were not officially rostered but BA staff were given the opportunity to change shifts to cover these starts. It then required discussions with unions by BA, as it resulted in roster changes for earlier starts but a large number of staff members liked these as they could finish before midday, which if it was your last day before days off, was ideal.