Should I buy tier 2 runes now or wait till I can buy tier 3

Hello, as the title says, I was wondering whether I should buy tier 2 runes or wait for tier 3, I am currently level 17 and have 5 champs. I know that runes and masteries affect your game a lot now with season 6, so this led me to delve into concept of runes xP.

In all seriousness though I don't know much about runes, how much they affect your game. I was wondering if i would do very poorly in draft mode (when i get to it) if i had none. Since i am not level 20 yet i can't buy the tier 3, but at least i will know if i should start saving/ buying less champs on impulse depending on your answers.

I know these are kinda a noob questions, but thanks for helping me out anyways ^^!!!!

... Btw this is a remade discussion because the same one got deleted for being on the wrong board and i didn't know if it was still available so i remade it. If this was a mistake pls inform me thx ^u^