That would be near the end of episode 6. Sage is sick in bed, the mc plans to visit her to cheer her up, but then Jill drops around unexpectedly for a birthday picnic. You'll see that scene you're looking for if you cancel your plans with Sage and go out with Jill.
There are repercussions to doing this. You can read about them here:
Choose Jill or Sage.
I doubt it will go very far. Whether or not she is romantically involved in the mc, she does quite like him, and she's doing Tybalt "a favour" so that he makes sure "Trent" doesn't go to the police about the whole mansion "fire" fiasco.
I do believe Jill is starting to realise she's been duped by Tybalt. Her freaking out to Bella, asking for help, and that entire exchange, Tybalt's chances are pretty much fucked now.
It'd be such a fucking awesome, simple solution, if she just went up to Trent quietly to talk about the situation only to find out he doesn't know what the fuck she is on about. Then she can just ram that watermelon right up Tybalt's ass!
My guess is, similar to Sage, even if you've avoided Jill all along, she still likes the mc and further chances will be presented. That way her going out on a limb for the mc isn't so sad, 'cause she still cares very much for him.
Just looking at that exchange between Bella and Jill, there were two parts that made me chuckle:
Bella: "I loathe Tybalt."
Jill: "I know that you don't like him."
Bella: "No. You're too kind with your words."
Bella: "I had him pegged from day one, and I've tolerated him for you. But that ends now."
Jill: "I never asked you to tolerate him."
Bella: "You tell me to be nice."
Jill: "Well, yeah. You're staring daggers at him every time you've seen him."
Bella: "That's me being nice."
and:
Bella: "He's manipulating you into getting what he wants from you."
Jill: "And what would that be?"
Bella: "You are so naive."