I can't get Utako's lvl 3 event to trigger. I tried waiting 18-19:00 in the library, outside the library, also tried it while following her step-for-step. The gallery of the event showed it beginning in the MC's bedroom, so I tried that too. Is it supposed to be the 2nd Saturday after the hint? Does another character need to be unlocked before it starts, or did the book quest lock out her event?
I brought her to Lilly and put her in Doll/Slave mode a few times, but she's still a virgin, and still talks about her imminent wedding, so I don't that's been interrupted.
EDIT: Turns out she was already spoken for after all. I reloaded the day and met her earlier and ended up attending her wedding.