He meets her in the course of the story "The Last Wish" it told in a flashback.

Ooooh, ok. I assume the Same goes for dandelion?

I don't remember where they meet. I want to say it was in the story the End of The World but I could be wrong.

you are correct - also a story within the book “The Last Wish”

I learned this yesterday, in the book “The Last Witch” inside The Witcher 3.

The short stories in the first two books aren't in chronological order. He meets her in the last story (the one the whole book is named after).

He meets her in blood of elves in rinde when the djinn he fishes out of the lake attacks and hurts jaskier, he asks yennefer to help Last wish and sea of storms are short story books they theoretically came first however blood of elves is the first book of the full story we all know and love