Where do I put the joints ... see basic layout

[wbmkk]

I hope to start my first major tiling job soon and need some help regarding the tile layout.

Here's a plan of the bathroom window wall (not to scale though)




I'll be using 250 x 200 tiles (250 ht, 200 width)

My intention was to have about 1000mm only of tiles, ie this the height above the level of the bath top.

Horizontally, I was going to start at the centre of the window, with a grout line there, but this may leave a very small gap at each end, next to the side walls. If I start with a full tile, ie over the centre line, small gaps may be left at the edge of the window.

Should I just offset one of these by, maybe 50mm.

Regarding vertical joints, where should I have my 'base line'

thanks

 

[PrenticeBoyofDerry]

The rule for setting out is:
Find your centre line, then from that you either start with the central tiles being half a tile either side of the centre line, or full tile either side.
You are trying to avoid, slither tiles in the corners. But you also want to avoid having them around your window reveal, so some compromise maybe required.
You try best to use the focal points, when setting out. The problem you have is that the window is offset with the wall, as is the basin with the window.