As early as possible.
When it comes to anti aging, prevention is ALWAYS better than cure.
And you want to start preventing as early as possible
So what's the best time to start?
Directly after your puberty ends
But you don't have to go so deep into it by spamming your face with anti-aging night creams, toners, facials washes, etc. if you're that young. Just get yourself an anti-aging serum or moisturizer.
And sunblock is a must during the day
Look for ones with a minimum of SPF 30 and PA ++
People may tell you that you should not be using anti-aging products at 19, but trust me, they're wrong.
An early start is always better, unless you wanna rely on botox when you grow old.
And you may not know this, but botox is actually a toxin that paralyzes your facial nerves. Trust me, leave botox as your last resort, and start getting your anti-aging serums.
Prevention IS better than cure