Start with a(n online) coach for 2/3 days a week, have a nutrition plan which you stick to, then I would say 5 weeks, maybe a little bit sooner. If you freestyle everything you can see results too but it takes way longer. I started weight lifting at 22/23 and got a trainer at 28 (I didn’t invest sooner) and saw results in 3 months that I didn’t make in all those years before combined.