At the stage of lining things up before cutting.(showerboard)
In the attached is there any reason why the shower enclosure should not
sit nearer to the outside edge of the shower tray or should it be
centralised on the tray lip / wall or whatever it is called.

Green lines are the tray lip.
Blue line is the trim centralised on the lip.
Red arrow where I would like to move it.

http://i64.photobucket.com/albums/h1...psezjhqvre.jpg