One thing I would add: You start every s-link with 'You decide to spend time with Twilight'. This is fine, and is where it will begin, but you could also open with customized pre-read first if you like.
For example, when you click on Twilight and are about to start S-Link 3, you get this message first:
"Twilight is hard at work in her usual place by the counter, with a pile of books on either side."
"She doesn't seem to notice you..."
Then you get to choose whether or not to spend time with her.
It's a nice way to let the player know 'hey, this isn't the default message, meaning story will happen here'.
But if you don't want to write them, they're only two sentences anyway, I don't mind knocking them out.