This one is true.
By the time your 20s roll around, it is safe to begin using anti-aging products on skin, and at the very latest by the time you hit 30. Over the counter products that include antioxidants are best for young skin, retinols for those in their mid 20's to early 30's, and then stronger stuff that combines antioxidants, retinol and other wrinkle reducing products for mid 30's and over.
And there is no age to start using SPF. Everyone from 1 to 100 will benefit greatly from daily sunscreen use.