That's fine. Here's the timeline: Before the party, Liliana decided to follow a satyr who left their frat-house. She texted Brand, asking for backup in case things went wrong. Brand (who had been spending the afternoons sitting in the campus library, waiting in case anyone needed backup like this) then texted the rest of the group, letting them know what was happening, and that he'd be busy for a bit backing up Liliana. The whole thing was pretty uneventful, though.
If you want an idea for what to change the post to (if you want to change the post), you could always describe what Mateusz and Helena were doing in the three days before the party.
@Kish, I assume I need to roll something to work the crowd like I'm planning. I'm guessing Charisma+Presence, or maybe Manipulation+Presence?