The benefit of having the sink in the middle is that you can stack dishes, etc on either side. But really, you can put it wherever you like. Good luck!

NKBA recommendations are a minimum of 24" on one side and 18" on the other. But, to increase the usability of the layout, you'd ideally like to separate the prep and cleanup functions better. So, that 24" on top of the DW (plus a panel) finishes off one end, then the sink, and then you have a much larger area dedicated to prep. That's the primary time consumer in the kitchen, and with a large area dedicated to it, and not having the DW in the middle of it, you just increased the utility of your kitchen. Two people can now use the sink simultaneously, with one loading or unloading the DW and the other prepping for a cooking activity. So, you gain much better function by offsetting the sink in the island than you do with a rigid adherence to symmetry. I'm a function over form kinda person, so, that's what I would recommend for someone who uses their kitchen for cooking. (Don't laugh, some people just want something pretty and never cook.)

It needs to go where it is needed.