Originally Posted by corporate-wage-slave

That's what people typically do, and egged on media / social media advice, but actually it's usually disastrous when that happens. Staff levels are planned for particular throughput levels and if everyone turns up an hour early then (a) it's the same number of passengers to process and (b) the staff to process this extra surge won't be in places (c) people who turn up at sensible times get impacted and hence (d) it's worse than counter-productive. Therefore the airline's advice will typically be "check-in at the usual time and certainly no more than 3 hours (2 hours for shorthaul)". If there is a risk of this, HAL will put up their tent outside and only allow admission at 3 hours to departure.

The best way to minimise problems would be to use Airportr to take any bags off you, or to check as much into checked luggage as you can, knowing that this may be delayed by the time your arrive. The other option would be to start at a domestic location (but not JER) and go HBO, since the screening will be done at that airport rather than LHR. But to be honest between HAL and BA if this is going to be an issue the workload - flights in other words - will be cancelled to fit the airport's ability to process. I wouldn't expect to see any plans for this before about 27 March.