when everything is right carry on with your horizontal rows utill the wall is tiled. make sure you use a straight edge on the front of the tiles to make sure your levels are correct. also make sure your cuts for the window are level on both sides, the top and bottom, don't just do your cuts at whatever angle your window is currently at, this leaves a perfectly square window, leave an overhand of one tile thickness so that when you put your trims in this leaves room for your reveal tiles and adhesive. If the window is out of square pack the difference out with adhesive (this will have to be bagged cement based adhesive as most tubbed adhesive has a maximum bed of 3mm but most bagged adhesive can be used up to about 50mm). Hope that isn't too complicated? Thanks for your reply. I have replaced all the wallboards so everything is nice and square, including the window, I was just a bit confused about doing around the window. As you suggest I will lay things out to see where the cuts will fall best. So when I start, from floor up and reach the window sill should I take a colume up either side of the window ( making sure of good levels both sides) then once at the top tile in over the window meeting in the middle ? This is where a mate of mine went wrong with his, the space left for