The sooner you start, the better it is! I tell everyone that you absolutely need to use your sunblock. Start at an earlier age so you don’t get premature ageing signs. There are two kinds of sunblocks; physical and chemical, the latter obviously contains chemicals which help absorb sunlight and transform it into energy, that’s how it protects your skin; it doesn’t penetrate into your skin.
A physical block literally reflects the light off your skin, these are those that usually leave a white cast on your face post application.