Resins from the wood will also stain. Warn everyone that the floor will be stained. Do it verbally. Do it often. Signs don't work.
Finish work is a critical time.
Paints can bond with the sealer on the concrete floor. Areas of the floor that are stained must be completely protected. Adhesives in the tape strip the stealer off the floor. Painters can use 24 hour tape and craft paper along the edges, and protect the field with drop cloths. Scoring can be done before the walls are up if you wish to have the pattern run under the walls.