Already tried it, it doesn't work but you were almost there. What you wrote made me think there might be an error in the game. So I chose "Skip to party beach party". The MC went to bed and slept, then the next day (Sunday, not Saturday), the MC woke up and got dressed, then put on his swimsuit and went to the beach party.
In conclusion: the party is on Sunday, not Saturday. So there is an error in the game, and I think I may also have a little translation problem that tells me this button is for not seeing the event. No wonder I'm going crazy.