Golden coat

Question
I have a 5 month old golden retriever.  When we bought him he was so fluffy but
now he seems to be developing a courser adult coat but it is very short and he
hasn't any feathering yet.  His parents both have longer coats with  feathering.  
From afar, my dog almost looks like a wavy haired labrador.  Will his coat
lengthen in time?

Answer
Interesting I have had 2 such similar questions today. Yes.

''    
Hi, my golden retriever is about 5 and half months old, and she's pure breed but her fur still hasn't grown. How long does it usually take for a golden retrievers fur to grow to the norm we usually see on golden retrievers?

It isn't a problem at her age, but I am not sure when the adult coat does come in.  Perhaps it won't be until fall when her winter coat comes in.''