Whenever Jin would go over to Gohan's house, he and Goku would spar, and Jin would always give him pointers. After Gohan found Goku he'd always been curious on what he was, and when Jin came, he'd been informed on everything about Saiyan's and had cut Goku's tail off, so that he wouldn't transform in a massive ape
At first Gohan didn't believe Jin, but thanks to the fact that Jin had long since gained complete mastery over the shift, he could turn into a 100 meter tall ape, at will. Gohan was shocked at the sheer pressure that Jin gave off, and almost passed out
Jin would come over once a week to spend some time with him, an even introduced him to Bulma and her family... and yes Jin had 'the talk' with Goku, so he knew what girls were, and didn't need to pat them down there
Gohan's Home
Jin: Hey Goku
Goku: Jin your here, train with me!
Jin: .... I just got here little bro, sigh.... alright
Jin had made a small fighting ground near Gohan's home for Goku to train in. However he didn't give him a gravity chamber, as he didn't want him to get too strong too fast and mess up the timeline
Goku and Jin would spar to for the next 5 hours, with Goku who would be going all out, and Jin who'd be fighting with just his tail the whole time. Goku was drenched with sweat as Jin was just reading a book with one hand. Jin knew that he'd make Kakashi proud with the way he was acting
Although he felt a bit bad for playing with Goku like this, Goku felt differently. He saw Jin as an elder brother, a role model and a teacher. Whenever he'd spar with Jin, he'd always be amazed by how strong and skilled he was
The thing that Jin found hilarious was that as of this moment, the Briefs were all stronger than Goku... Hahahahaha
Goku: Big brother! How'd you get so strong?
Jin: I just kept training and never ever gave up
Goku: Do you think if I keep training I'll be able to get as strong as you
Jin: Of course Goku, but remember that you can't allow training to rule your life. You need to have an education, and a good job
Goku: But why?.... why would that be important?
Jin: You see Goku, If you strain the mind so much on training, you won't be able to go forward as well as you can. You need to take breaks from training, allowing your muscles and mind to rest, so that when you do go back to training, you progress much better, who knows... you may even come up with some new techniques
Jin said that last part using telepathy which caused Goku's eyes to have stars in them, as he stared at Jin in awe
Jin: Hey Goku, tell grandpa Gohan that I won't be staying for dinner, as i have plans.... Make sure to have a bath, and use soap
Goku: Okey!
Goku then ran into the house as Jin was just smiling at how much of an impact he'd had in this world. He wanted to see everything this universe, and all the other universes
Jin teleported back to his room where he showered and met up with Bulma who was in the lab working on something
Jin: Hey Bulma
Bang!
Bulma: Owieeeee... Jin what did i say about sneaking up on me like that!
Jin: Hahaha I'm sorry
Bulma pouted as she glared at him, but seeing him rubbing his head sheepishly caused he to sigh before she crossed her arms
Bulma: Sigh... so what's up?
Jin: Well I was wondering if you were free tomorrow, maybe we could do something?
Bulma: W-w-w-what like a d-d-d-date?
Jin: Yeah a date... so, is that a yes or no?
Bulma: Yes yes!... I mean cough yeah sure I don't mind
Jin: Great, We'll head out at 10 tomorrow
Jin then left the room, and when he was some distance away he could hear Bulma start to squeal, which just caused him to chuckle
Jin went back into his room and layed down, he used his godly ki sense to be able to feel everyone in the Universe. Jin's mastery over ki was astounding, and would even cause Whis to praise him. He could feel where everyone was, King Kai was on his planet driving his new car in loops, Frieza was at one of his spacestations probabaly plotting what planet to take over next, and Beerus was asleep on his planet with Whis sneaking out every now and then to find some good food.
'Maybe i should go an see Whis... he would be able to help me get stronger by being a sparing partner, and if he doesn't want to teach me, i can just show off some of the cooking skills i've made... Okay i've decided that after my date with Bulma I'll go an see Whis and train for a bit'
Jin had also wanted to go to Universe 6 for some time now to see Planet Sadala and meet some other saiyans and fight them. Although he wouldn't train them, since he didn't want them to figure out Super Saiyan before Goku did. (A/N: When he does go to Sadala, Caulifla will be 15 years old, it may not be her age in the anime but i dont care, she'll be 15 in this, the same age as Jin and Bulma, also if anyones wondering 21 is currently 28-29 years old, but who cares when you can have eternal youth right?)
Jin slept well knowing that he'll soon be able to make waves in the universes and stand out in front of everyone, maybe even become the next God of Destruction... or something else altogether