How early to arrive for a flight from PRG?

I know it's a long shot, but there are at least a few people who post from CZ, so I'm hoping someone can help. I've got a few people flying here in a few days who've never done much travelling, and someone told them to be at the airport (PRG, in Prague) 4 hours early. That seems ABSURD. They're flying from PRG to LHR, and then on to IAD (all on British Airways). I can't seem to find anything that would suggest any longer than 120 minutes.

They leave PRG at 8 AM, and the notion of needing to be there at 4 AM seems insane. Anyone have personal experience to weigh against this? Is there any reason 120 minutes isn't plenty of time?

(it's 2 30-somethings and a 4 year old, if that makes any difference).

could be they need to leave the city 4 hours early. airport is way on the outskirts, depending on where in the city they start from and whether they take a cab or public transportation it can take well over an hour to even get to the airport.

i havent been out of there for a few years now, but i showed up 90 minutes before usually, sometimes less then 60 if i wasnt checking a bag.

if they arrive at the airport 2 hours ahead of time i wouldnt worry at all, even with a 4yr old.

I flew from prague to stavanger on Norwegian airlines in the spring. The check in didn't even open until 2 hours before the flight, but getting to the airport took longer than I was told (like an hour instead of 30 mins) so the 4 hours might be when you want to start heading to the airport. so yeah 2 hours early is plenty of time.

Sweet, thanks. They're actually driving in from about 4 hours away (near Ostrava, if it helps), and the fact that they're planning to leave at around midnight for an 8 AM flight is dumb. I mean, the better choice would be to drive to Prague the night before, but for some reason, they like their way better. I just figured I could save them a few hours sleep and get them to leave at 2 or so, and they'd still be ok.