Normally you would place one over the sink. I like to place them so they line up with the edge of the conter top
so you dont cast shadows on the counter. What is the L shaped thing at the bottom right of your layout.. a 1 ft wide island? Or a wall?

I would recommend even spacing throughout the room. I would also add one over the sink and if you have an island I would make sure to install some over it for good task lighting. Food for thought, donÂt underestimate how many lights you need. The more the merrier. If you think they are to bright install a dimmer, but once they are installed it is difficult to add more if the room is not bright enough.

Here is a link that might be useful: Recessed Can Light Guide