I hope this is ok to ask, but a friend in wales has got a female golden, she is 7 they got a male puppy who is now  6 months old, he has asked me if the dog could be fertile, as he is getting his girl netured as soon as she has had her season. They are keeping them apart, as he has tried to mount her, but if they get together could he be fertile, he is worried to death, and may fetch him here for the time his girl is in season. Not having had a stud before, I am just asking on there behalf. I know in the past some breeders do use the new boys as young as 10 months, and have had litters. but could this be possible at 6 and a half months.

Simple answer is yes, best to keep them separated.

I have rung and told them, thanks it was my thoughts too

Your welcome.

I'd have to agree, keep them right apart just in case, if she's in season right now.   I've had a successful mating with a dog I'd only just bought in (at 5 months) when the bitch I'd intended for him, came into season.   He mated her when he was just under 8 months.  I was right there at the time and was amazed to see him 'help himself' - very unusual for my breed!   We just had puppies some 8 months earlier than planned!!  

It would be unlikely a puppy of only 6 months would be fertile, even if they are 'willing'.   But you never know!

In my breed males are most definitely fertile at 6 months of age.