Is it possible to get a transplant at around 20 years old if you have been on Fin for a couple of years, and had been able to stop further hair loss? Since Fin stops hair loss, and transplants are recommended for people 25+ in order to see what your balding pattern will be, why would you need to wait that much longer?
Never a good idea. Take a look at this: https://baldingblog.com/need-master-plan-think-hair-transplants-photos/ You must have a Personalized Master Plan in the case that your balding pattern follows this man. If he started at 20, he might have used up all of his donor hair before the balding became complete. That means that he might not look right, hair wise. Good planning starts when you begin the hair transplant process and you MUST know your lifetime donor supply.