As the old saying goes, an ounce of prevention is worth a pound of treatment. But when it comes to skincare, when are you actually supposed to start using certain anti-ageing products, to get the most bang for your buck? Too early, and you might be unnecessarily wasting money and not actually making much of a difference, based on the biological need not being there; too late, and you might end up spending more money to counteract problems. So what's a gal to do? We enlisted the help of Dr. Elizabeth Tanzi, board-certified dermatologist and co-director of the Washington Institute of Dermatologic Laser Surgery in Washington, D.C., to set the record straight on when you actually need to start using specific anti-ageing products. The answer might surprise you for some of the products, so keep scrolling to see the official dermatologist opinion!