It's easier to do it the way you've done it, in my opinion. To do it the other way, you have to work in advance how far your reveal tiles are going to be sticking out from the wall, to make sure the edge of the trim lines up with the a edge of the tiles. You also can't get much of the trim's lip against the actual wall, as you are overhanging the wall by around 10/12mm, depending on
tile the thickness, so the trim tends to move around, until you do the reveal tiles.