Who first?

Cynthia

Seeing as Sam had been the first Guinea Pig, Josh decided to experiment on someone else and eventually decided on Cynthia. He clicked his fingers in her face but, similar to Sam earlier, she just continued to look at her watch. Thinking of her watch, Josh looked at it and noticed it was completely still; wanting to test something, he approached Billy Stone, the Student sitting in front of Miss. Bronski, and lifted up Billy's arm so he could get a look at his watch.

He noticed the time on Billy's watch was identical to that on Cynthia's, even down to the position of the second hand. He also noticed that, when he let go of Billy's arm, it remained up in the air, still at the angle he'd been holding it at, as if Billy was choosing to do so.