Fra www.KLM.com
"Check-in times and rules
To make sure that you can depart with your flight on time, you need to be checked in on time.
This means that you need to take the following into account for all check-in options::
For KLM flights within Europe, check-in closes 40 minutes before departure; for KLM flights to and from Europe, check-in closes 60 minutes before departure (with the exception of Paramaribo).
You must ensure that you are checked in, in possession of a boarding pass, and that you drop off your baggage before the indicated check-in deadline. This means that you should leave sufficient time to find your way around the airport and account for possible long lines at the check-in desk.
To facilitate a smooth, comfortable check-in, we recommend that you keep to the recommended check-in times as indicated. Depending on which airport you will be departing from, you will need to calculate between 2 and 4 hours.
If you check in after the indicated check-in deadline, you run the risk of losing your reserved seat and therefore not being allowed to board. You will also lose any rights to 'denied boarding' compensation.
If you are waiting in line and expect that you will arrive too late to check in, please let one of the KLM employees know."
Men man bør vel ikke være så stivbent at man ikke lar folk reise når dem kommer til innsjekk mellom 30 og 45 minutter før avgang! Det er mer en nok tid for innsjekk, og shopping før flyet går!