If you first put porcelain stoneware on the floor and then within a couple of weeks you put porcelain stoneware on the walls, do you have to grout the joints on the floor separately first? Or should I lay the whole bathroom and the floor and the walls first and then grout the whole bathroom?
Do it your way, people lay the walls first to avoid staining the finished floor.
But if you are careful and cover the finished floor with screed, you can start from the floor. I prefer it this way, and I grout the joints on the floor straight away.
Lay the walls first, except for the lowest row. Then the floor. Then the bottom row on the walls (taking care not to smear the floor). And after all that – grouting.