I'm often an early riser - esp on Int'l travel with jet lag. Not unusual for me to go to the lounge right when it opens - have coffee, maybe fruit & pastry...then partake of the full breakfast later - either also at the lounge or in the restaurant, if offered.
I try not to "abuse" it - the 1st one is very light...never had a problem doing that

That is for Diamond/Glob...I don't know anything about staying on the Prive rate and how they might treat that.