Quite coincidentally, I am in the club as I write this.
Schiphol Amsterdam Club opens at 7 am, closes at 11 pm, every day.
Breakfast served 7 am to 11 am. Hot snacks served at 5 pm until they run out (usually around 7:30 pm, sometimes much later). Pastries, chips, fruit, beverages (including complimentary beer and wine) available all day.
Usually very helpful person at desk. Club level guests can check in / out in lounge. Definitely an above-average lounge in Sheraton chain, and I've seen most of them.
RA