Henry Cavill has been balding since his late 20's and Jude law has been balding since his late teens.
Regardless if you are predisposed to becoming bald in five years or fifty, The idea of a hairloss treatment protocol is to delay that process and stabilize your hair to maintain the lowest Norwood level possible for the longest amount of time your genetics will allow.
Waiting until you have reached an Norwood 3 or above before you start treatments is the antithesis of this approach.
@Oliver2004 going back to your original post, you are only 18, read up and educate yourself on the treatments available if your hairline starts to move then at least you will have the option to take them if you so choose.
but like others have advised at this point monitoring your situation is the balanced option, as nobody can predict with any certainty where your future hairline is heading, it may well hold in its current position for several years before you need to commence actual treatments.