It looks like you will also have another hanging fixture over a table near the island. I might use two instead of three for that reason since they are fairly large. Hang a piece of paper in the size and shape of the lights from a string taped to the ceiling. That allows you to step back and see how you like the spacing. If your sink is centered in the island though, you may want 3 to have enough light. The ceiling lights seem fairly minimal for a kitchen. If the sink is off center, as it appears, 2 lights evenly spaced on the sides of the sink might be better than 3.