500 Days of Kristin, Day 34: Kristin Was Thrilled to See This on Twitter Allie Jones · 02/28/15 12:29PM There are 466 days until Kristin Cavallari's biology textbook Balancing on Heels hits shelves, and today, Kristin shares with us another blockbuster report from the scientific community. In a post on her eponymous app, she writes: