Born in Philadelphia, Pennsylvania, Timlin debuted on the big screen as Amy, a 14-year-old girl with diabetes, in the 2005 film Derailed alongside Clive Owen and Melissa George, who played her parents. Timlin played Maddy in a short film, The Isabel Fish, directed by Lara Zizic for the Columbia Film Festival. In 2007, Timlin appeared in the music video, "Sleeping Lessons," by Albuquerque, New Mexico based indie-rock band, The Shins. In 2008, she made an appearance in the music video for the song Check Yes Juliet by We the Kings, playing the fictional Juliet. She was cast in the short-lived CBS television drama, 3 lbs, as Charlotte Hanson (the daughter of the main character played by Stanley Tucci), in three of the eight episodes that were filmed. Timlin is seen in the short film Man, written and directed by Myna Joseph, which was screened at the Sundance Film Festival and at Cannes. In 2008 she played Emily Draper in the ABC television show, Cashmere Mafia, the troubled teenage daughter of Juliet Draper (Miranda Otto).