Hola Block;
Try Hunters or The Coin on the Warmoesstraat, just a couple hundred meters from CS. Both technically open @ 07:00, but give them a few minutes sometimes to get there and set-up shop... I think they have re-branded The Coin into Coffeeshop Hunters or Hunters Coffeeshop whichever the other one was not named...
Here's the link:
www.hunters-coffeeshop.com/