Perhaps as a guideline our approach:
We received the Q2 plastering from the general contractor. Ceilings on the ground floor (concrete) and upper floor (drywall) were unfilled and not sanded. Bathrooms had lime-cement plaster.
We hired a painter through MyHammer, who primed the entire house, filled and sanded the ceilings, and filled and sanded the bathrooms ready for painting. We then only had to paint. The ceilings on the ground floor were additionally wallpapered with fleece.
We paid €4,000 plus 5 buckets of professional white paint for our own painting.
Oh, by the way: Our house has 2 full floors with 145m².