Check-in: When do I have to be at the airport for check-in?
Always be there in due time. Better with 1 hour too much than 5 minutes too late! Check for official check-in rules with the airports or airlines directly but be aware that traffic could delay you, the check-in lines could be extraordinary long and security gates could be suffering from extreme waiting time.
A rule which works in most cases is to be in the airport 2 hours before for flights within Europe and 3 hours for all other flights.
We recommend you do your check-in online or use the check-in kiosks and if possible and relevant also the baggage drop counters to avoid waiting too long in a check-in line.