[maonnjtip]

Salam `Aleykum,

An easy question brother, this is because if you review how the Quran was revealed, you realize that Allah (swt) reveals the verses each in a related occasion, meaning he knew that the blind man will come and say what he says and he revealed the verse in that time... All verses were revealed in this way, this is not the only one, for example when his companions came and asked him (SAWS) about how to divide the war booty, then Allah revealed the verses about the war booty, of course he could have done so before but this is how Allah decided to reveal the Quran, and this is why there is something called "Reasons for revelation" and we know the reasons of revelation of many verses.