They did both sets of stairs for us.

We got there two hours early. After checking bags we drank a bottle of champagne outside the terminal for a half hour. Went thru security in a flash and sat at the gate for about an hour.

Alot of flights including the KLM Amsterdam job in our gate house departing before us.

3 hrs sounds excessive
2 hrs sounds safe and generous
1.5 hra sounds like minimum for intl flight

I would check bags as early as you can get away with and visit Sunset or Karakter.

Just my opinion make your own decision after weighing facts on when to arrive.