Not wanting to raise suspicions by possibly changing Jamie again (assuming its the watch that did it) you decided to test it on another sibling. Danny your 10 year old little brother looked like a good candidate. You wanted to test something more drastic with him, so in order to avoid surprises and panic, you decided to wait until everyone were sleeping and then you walked into the bedroom he shares with Michael.
You find him snoring a little on his bed, he was wearing a wife beater and briefs. You carefully walk in until you're in front of him. You pointed your watch towards him and tried to moved the clock forward 3 hours, however in your anticipation slipped it a lot farther changing the time from 6:00 to 12:00 on accident. You watched on as his body began to stretch rapidly.
Unlike you, Danny was short for his age at 4'6, but it didn't look like it would stay that way. He grew taller and taller, soon you could see the beginning of hair sprouting through his bare legs which grew out into lanky poles. "I wonder..." You muttered while you slowly and carefully made him put an arm over his head and exposed his armpit. The bare skin was starting to get some hairs too. Danny shook a little as he adjusted to his bigger frame. He must have been about 13 or 14 now, and almost two feet taller. You took a few steps away from your brother, so you can get a better look of him. The former boy now covered his whole bed and his snoring was getting deeper as he goes through puberty.
His thin limbs were beginning to get some meat as his muscles developed. His thighs, calves, biceps and shoulder were broadening like any normal sturdy high school young man would do. His exposed armpit hadn't just a few hairs anymore but a full thick bush. Some facial hair and acne could be seen on his face while his wife beater started to pull upward and reveal a treasure trail on his belly. His feet had grown from his former size 6 to something like size 12, and now they're poking out of his bed. Judging by his look, Danny must be 16 years old now, just the same age as you. He looks like a guy who could be taking classes with you.
You can hear him moaning in discomfort, it was subtle but you can notice his voice was deeper now. Maybe he was feeling uncomfortable because his clothes are small on his bigger frame. His wife shirt was now barely covering his chest while his briefs had a notorious bulge that's stretching its white fabric to its limit. You can also notice that some bad smell was emanating from his thick bushes on his armpits as well as his bigger feet whose toes had some hairs poking out there too. You can relate to all that stuff but for now you must decide what to do.