Watching povs and finding a mentor would def be a good start

There is no "ready." He can start comp at any time. I recommend Newbie Mixes.

just play the game bro and when u feel like u hit a wall consult someone who is better than u its that sinple really

ok you are wrong here as i said previously he doesn't know the basics (he asked me how spy works). i dont want him hopping in newbiemixes with him having absolutely no experience on any of the other classes. im asking how do i really kickstart his learning so where after he has done the basics he gets right into the comp scene instead of loitering around in a casual state (the key reason he installed tf2 was the idea of ultiduo)

Teach him how to count uber and explain uber advantage and disadvantage (this array7 vid is decent at explaining uber count https://www.youtube.com/watch?v=QhEyIqGPhPg)
Tell him to tilt his camera slightly up so he can see bombing soldiers
Teach him common map callouts (a decent resource would be the map pages on comp.tf, process for example: https://www.comp.tf/wiki/Process)
Try to explain crit heals (he just needs to know if someone calls crit heals, then try heal them)
Try to explain what surfing is (both explosive surfing and bullet surfing)

Explaining all of this stuff at once may be overwhelming, so I'd recommend telling him one concept at a time then giving some time so he can learn one thing then move onto the next. However just playing the game and picking up information from teammates will work just fine. (i.e you can learn about callouts from listening to your team talk).

EDIT: just keep playing pubs and random modes and have fun whilst he can organically learn what each of the classes generally want to do and how they function.

teach him to rocket jump, basic movement ability is the defining element of competitive gameplay

Ulti is really simple to pick up and play with friends. My partner had never touched medic beforehand, and ended up having a lot of fun. Granted they know more about the rest of the game, but I think if your friend knows how to use a bow and saw and you don't stack the teams against him, he can learn and have fun.

I would wait until he understands more about the pub-level mechanics of the other classes before trying to pull him into 6s or 9s, personally. I think having fun in the early stages is precious, and wouldn't want to immediately introduce the grind or throw him to the wolves (like hearing people mald in PUGs or whatever).

make him watch medic and soldier ultiduo povs. he should also play soldier sometimes so he knows both of the roles and what they can be expected to do. he might want a config and a hud eventually. also is does your friend happen to come from any other fps? csgo maybe?

The Art of Medic could be of use to your friend

make him play other classes so he isnt donkey at fps game's and can understand what they can do to him as a medec

have them play the game. everyone who's good started off by playing the game and learning what stuff was, if they don't know the basics of the game then the best way to teach them is to play with them and maybe answer any questions, it's not complicated and should not be difficult, it just will undoubtedly take time.

if he doesnt know what spy does just get him to pub. no point shilling someone into competitive if they dont even know what the game is yet

thank you all for the helpful posts, i have started with him using some of these and will continue to. just 2 days ago he said "yeah sniper is kinda fun" despite him having not great aim