depending on what lights you've already got on there and what you keep I'd say anywhere from 40% blue up to 60%, and 20-40% whites. Lower is better starting out but the best judge will be to see how your corals react
Agree with the above. Part of it also depends on if you have optics, wattage of the LED's, height above water line, and depth of the corals in the tank. Starting lower is better. Just keep an eye out for any signs of bleaching and increase about 5% a week until you get results you are happy with.