just keep skipping days over and over and here events will eventually show up when you try talking to her. One of her events is at the hot spring but that event will say Lucia is at the hot spring when you wake up that morning.
O.k., I have maxed all girls stats, all titles, I think a total of 40 days have passed and still no Lucy story, I check in for dialogue options almost every hour (morn/noon/evening) and nothing changes. Only options is generic "how are you doing" & fuck in the laundry room.