When to read Wind Through the Keyhole

So I've just started to join Roland on his journey to the Dark Tower. I finished The Gunslinger, then went and got the other 7 books. I'm currently on book 2 so hold up on any spoilers, but I wanted to know when should I read The Wind Through the Keyhole?

Do I read it after Wizard and Glass or will it spoil later books and I should just read it after Dark Tower?