S
Spud
I am guessing you mean prime the area rather than pvaI don't use anything else but kerraflex nowadays (as has been already said a few posts up). Anyhow, my tip for angled wall/ceiling to flat ceiling is to PVA said angled area, then apply the thinnest coat of adhesive. When dry this will give immense grip when tiling, as no-one wants a 60x30 landing on their toes!
Taking the back edge off the tile is also the proper way but for safety's sake only use a machine with capabilities for cutting angles. I recently got to finish a job after the original tiler tried to cut angles moving the tile and not the machine. It got caught in the blade and chucked the tile up under his chin!
Jel