I like to set a batten around the room at the height I want the second row to be and tile the walls up from that. This means you can’t accidentally damage the floor (‘cos you have done it yet!)
Then tile the floor.
Then do the row of bottom cuts for the walls, I like the idea of wall on top of floor (like tiling a roof) and I find it easier to get a neat finish this way. Can get a nice close junction that can be done in clear Silicon if that suits the job.