The only way to know for sure is by trying it. There are earlier flights out of AMS before yours, making it more likely that they will accept your bag. A friend who lives there was able to do this just last week, attend his meeting bag free, and fly out AMS-LHR-JFK later on that afternoon.

I would not guarantee this will happen every time as IIRC the rules for CE bag drop times are supposedly 3 hours prior. Hopefully you will have better a experience at AMS than others have recently had according to reports in another thread. I don't know AMS that well myself but if there is a left luggage there maybe you could use this as the backup option.