As with any important paperwork, always have a copy on you.
No matter where I am going I have copies of the permits inside the gun case.
Most up to date info from KLM:
"During the trip, you will be required to have the relevant licence forms with you and to produce them when asked to do so. If you do not have the licences required with you, your firearms and ammunition could be confiscated."
Permits and licences - KLM.com
Most up to date info IATA:
"Arms and Ammunition regulations::
Import and export of firearms and/or ammunition requires prior permission from Dutch Customs. Passengers must hold such permits at all times."
IATA - Netherlands Customs, Currency & Airport Tax regulations details
Which Mirrors AH Safari Planner:
"Make sure to prevent your firearms from getting impounded by applying for the consent form for both the outbound and the return transit through Amsterdam. Customs are not going to even know that you are in Amsterdam as you are not entering the country. However, the Dutch Airport Police, who are the ones that are doing spot checks regarding the consent form, may contact you at the gate of departure from Amsterdam and ask to see your consent form. If you are unable to show them the consent form then your firearms and ammunition will be held by them until you get a consent form to them. Further, Northwest Airlines and their partners KLM have also received notice that check in agents here in the USA should be checking with passengers at check in to ensure they are in possession of the consent form before loading the firearms and ammunition."
AfricaHunting.com - Hunting, Bowhunting, Hunters, Bowhunters
We noticed that the police appeared to wait until the last minute. i.e.. within a couple of weeks of the flight.
Repeated phone calls at that point.
I'd be asking the Travel Agent for an update on the progress, unless the application was just submitted yesterday .
( I have had a few screw up on some important issues for me)