I'd go with .5 oz of the Columbus at 60min. Then .5oz of each Cascade and Citra (so total of 1 ounce) at 20/15/10/5/0 with 3oz of Simcoe for 7 days in a dry hop. I have made an IPA with a similar grain bill and the IBU are upper 80s with a full ounce of Columbus FWH. I use Amarillo with the Cascade instead of Citra, but was actually going to change it up next time and give Citra a go.
Really, though, it depends on what you like. I'm a fan of All Day IPA and Hopslam so that is want influenced my schedule. Research the beers you like and experiment a little. That's the fun, right?