For me at least, the more relevant question is when the first sex on the Filthy route will happen, for both the lesbian and straight characters. We know this is an incredibly slow burn game, with L&P going for scenes that are sensual, not pornographic. I believe it to be highly likely considering L&P's pace so far that some characters might not have sex with Sophia until the final few days of the game, possibly even playable day 30 itself.
And most of my arguments so far are that Sophia is nowhere near that yet. Especially with so many things at risk, like her job and marriage. She's still the loving wife of Liam. And in terms of Dylan, Sophia currently appears to be more concerned with setting him up with a gf that finds him attractive (like Marie or Emma) more than showing any signs of sexual or romantic attraction to him herself. Which pushes Dylan's chances with Sophia more towards the end of the game than closer.
As I've said myself recently, unless L&P is actually just stringing us along, having at least the option for Sophia to fuck the four major characters (Dylan, Sam, Ellie and Patricia) is pretty much certain. It's just more about the journey getting there than the destination. And we're only at the start of playable day 12 next update. Of 30 days.