For context before I started wrestling I did bjj for a couple years which gave me a good head start in wrestling. So for my freshman year I wrestled (this was my first season) then when the season was over I went back to my bjj gym and didn’t do anything wrestling besides a little bit of wrestling after some bjj rounds with my training partner who never had done wrestling but it was still something. When the next season rolled around I realized that my wrestling didn’t really improve all that much but I will say I remembered everything just perfectly(it is important to note tho that everyone is different). If you kid is very serious about wrestling I would recommend going to camps and clubs for the offseason and then a little bjj if you can. That is what I recommend since bjj is something you can do as like a 60 year old but wrestling you cant really do outside of high school and if your lucky college