(Playing with a classic setup of the genre here. For the purposes of this path, Jon received the stone over winter break, not spring.)
Jon was naturally wary as he arrived at Lakeview Academy that morning, on the lookout for any possible fallout from his unintentional wish. Nothing struck him as odd immediately, though Karyn had given him a thorough tongue lashing when he told her what he did:
"SERIOUSLY JON!" Karyn had whisper shouted at him as they walked to school. She grabbed at her new larger breasts "You already saw what that thing can do. It totally rewrote reality; I went home and every picture of me has blonde hair, my mom has blonde hair and big boobs now. I mean, it's a good thing all my bras still fit, but something that can totally change history is scary, and NOT something you should use willy nilly!"
"I know, I know," Jon said guiltily as they finally arrived at school, "I'm going to be super careful from now on and avoid wishing until I can figure out whatever Something Interesting turns out to be." Karyn rolled her eyes but agreed and the two friends shuffled into Ms. Nakahara's homeroom class. It was the first day of a new semester, so the teacher passed out their schedules, which Jon and Karyn quickly compared to see how much their classes lined up.
"Oh good, we've go three together," Karyn said cheerfully.
Jon's brow scrunched together as he looked at his class load, "What's Empathetics?" He asked. It was an elective he didn't remember signing up for, but was apparently going to be his first period.
"Oh you know, it's that class about building empathy with others, supposed to be an easy A," Karyn replied breezily, "Isn't that why you signed up for it?"
"I don't remember signing up for it," Jon replied, "you don't suppose it's because of the wish, do you?"
Karyn put her hand to her chin in thought, "I guess that's kinda interesting, changing your electives around. Seems sort of weak though."
"Well it's either that or a scheduling mistake," Jon muttered but resolved to go to the class. He'd never even heard of something like that being offered, while Karyn seemed vaguely aware of it, indicating its existence might be due to the stone. In any event, he could live through a period of trust exercises or whatever in order to gather information.