Do we know how these two characters met?

Question

Has it been explained yet (perhaps in The Force Awakens novelization, or even out-of-world)…

…how Snoke and Kylo met?

In The Force Awakens…

I was under the impression that Kylo was found by Snoke only after he’d left Luke’s training.

However, in The Last Jedi…

…Luke suggests Snoke was the one responsible for Ben’s turn to the dark side, which in turn suggests he and Snoke were already acquainted in some way.

And of course, since…

…Snoke dies in The Last Jedi

…we might not learn much more about their history (unless The Last Jedi novelization fills in the blanks), but do we know yet how they met? Or even if they did physically meet initially or were merely somehow connected through the force first, only actually meeting after the key event we learn about in The Last Jedi?

Answer 1

Sorry, your "The Force Awakens" impression of "Kylo was found by Snoke only after he’d left Luke’s training" is incorrect.

From TFA novelization, Leia tells Han when they meet, and uses a Past future tense: "He knew our child would be strong with the Force. That he was born with equal potential for good or evil"

Leia bit her lower lip, refusing to concede. “No. It was Snoke.”
Han drew back slightly. “Snoke?”
She nodded. “He knew our child would be strong with the Force. That he was born with equal potential for good or evil.”
“You knew this from the beginning? Why didn’t you tell me?”

She sighed. “Many reasons. I was hoping that I was wrong, that it wasn’t true. I hoped I could sway him, turn him away from the dark side, without having to involve you.” A small smile appeared. “You had—you have—wonderful qualities, Han, but patience and understanding were never among them. I was afraid that your reactions would only drive him farther to the dark side. I thought I could shield him from Snoke’s influence and you from what was happening.” Her voice dropped. “It’s clear now that I was wrong. Whether your involvement would have made a difference, we’ll never know.”

So, while we don't know how they "met" face to face; it's clear that Snoke's interest in, and influence on, Ben Solo, happened far before he had that unpleasantnees with Luke.