You didn’t Indicate the height of your ceiling. With an 8ft ceiling it is a challenge because if you will be restricted to a smaller diameter. I only installed two over my 99” island. I wanted them larger in diameter, but the next size would not accommodate my 8ft ceiling. I did not want to use three, I knew that from the beginning. I wanted the lighting to be uncluttered and open. This is what I did.

As a general rule, odd number multiples work best. But that all depends on the size of the island and the size of the fixtures. If you want those fixtures pictured above, get two. If you want (3) fixtures, go smaller, i.e. no larger than 8" in diameter.

over the island i would rather see something like this, than individual pendants over the isalnd. for the sink, i would do one 'down' light. 3 to me is overkill and 2 will look 'weird'. are you installing under cab lights as well? with the undercab lights, it will help with the sink area. 'down' light another example(where all the light is down in your sink - none 'escaping' up or out of course get the fixture to scale with the space.

I'd think if it were centered it may look ok, but then light distribution may be funky unless you have more overhead lights you plan on using it might work.