Its all a matter of perception. You'd never know whether your 'preventative' measures are working or not if you are only 21.
It's all in the genes and how you are treating yourself - staying out of the sun, drinking enough water, getting enough sleep, eating proper foods, not smoking and if your parents look like they are 200 years old even when they are only 55 or if they look like they are in their 50's when they are really in their 70's.
Prevention should be wear sunscreen, wear moisturizer under makeup, don't smoke, don't do drugs, drink alcohol in moderation, eat, drink and sleep properly and wear good makeup.
She is 21 but she also relies on her appearance to be employed. She's got minimal talent so she needs all the help she can get to stay young looking so she can continue to play the teenage roll.