They are never too young to be groomed once they are in their forever homes.  I let that hair grow.  It is a pain to begin with until it does get long enough.  Be very picky about a groomer and very specific in what you want.  If you don't want them to trim the top of his head (and you probably won't), you better put it in writing and state it very clearly.  Tell them specifically how much you want trimmed off of his length and make it clear that he better not be shaved when you get him back.  If you have to sound like a b*&@! so be it.  I don't mean to be ignorant, but there have been some grooming stories from hell on here 
