Spring Fashion Week is officially under way, and stars like Gisele Bundchen and Jessica Simpson have already helped kick off the fun. There are more celebs who are scheduled to turn out in the coming days, as Justin Timberlake's showing his William Rast, Gwen Stefani will have a show for L.A.M.B., and Victoria Beckham's hosting a small event for her namesake collection. Mary-Kate and Ashley Olsen, meanwhile, will be at their presentation for The Row, and tomorrow we're helping them launch their Elizabeth and James pop-up shop. We'll be there with Fab and Bella tweeting from the scene, so make sure to follow us on Twitter for the latest news. So, tell us — which celebrity line are you most excited to see at Fashion Week?