I'm a 18-year-old boy. My question is regarding beard growth.

Beard hair is a genetic trait.  There is no medication to grow a beard.  Some try topical minoxidil but you would need to use it everyday and there may be side effects.  You should see a doctor before starting such treatment.

please dont  worry about that and wait until 20's for full maturity ... If you have still no beard  on cheeks than you may decide to have a FUE  for beard restoration . Even full beard, mustache area may be restored in one session of operation with 3000-3500 grafts in experienced hands . Unfortunatelly If you dont have hair follicle on your face skin  (genetical reasons ) no medication may help you.

It can take well into the 20s to establish significant beard growth. Much of this is determined by your genetics. I don't usually recommend minoxidil for an 18 year old male trying to promote beard growth. I will occassionally recommend for someone  older looking to enhance specific areas.

Minoxidil might work. Many young men want to accelerate their beard growth and ask about it. It takes age (genetic triggers which occur in family lines) so if you want to find out when your beard will grow out, you need to find out when your father or grandfather started to grow their beard. Hormones should have kicked in nicely by the time a man reaches 18 but he must wait out his genetics as hormone alone are not responsible for the onset of beard grown. Beard transplants can be done when the young man is a bit older (over 25) if the beard has not grown in yet