It's a journey worth starting early…
Learning to read is quite distinct from learning to speak and it doesn't happen all in one go. Kids are born with an innate curiosity, so with a little encouragement and a lot of books knocking around the house, you'll notice a steady progression in their reading development, with each new story piquing their interest and spurring them on to learn more.
They also can't hide how clever they feel when they begin to recognise words and accidentally begin reading to themselves, or even just noticing signs in the street, opening their eyes to all the stuff that's going on around them, but they hadn't previously noticed.