
Ditto what Dawn put & add Ringcraft or obedience classes are great places(if they are properly run)for you dog to mix with others in a safe enviroment. Have you got any friends who have gentle dogs that your puppy can mix with if you haven't got a local ringcraft or pet obedience ?
Are you thinking of showing your Dobermann or working in obedience(not enough other breeds in obedience in my opinion I love seeing other non WSD/BC/GSD etc working) Working towards the KC Good Citizens Certificates is also a good thing as it is based on your dog being a nice well behaved pet
Remember that your puppy will not have seen anything other than dobermanns & humans(unless the breeder had other breeds)so might not recognize other dogs as dogs, thats why my cavaliers think they are part BC part GSD & part Border Terrier & my next BC will also think he is part Cavalier, GSD as he will be living with them
I am not a great fan of puppy parties unless they are structured because if there is a very forward puppy(like my JD-cavalier)& a more inexperienced puppy like yours your puppy could become more frightened if they are all let loose togather. My Great Dane breeder friend had a lovely harlie bitch who adored puppies of any breed & would lie down & make herself the same height of a puppy if it showed any fear of her, she was responsible for my last collie loving all Great Danes & big dogs She would have been a great dog to have at puppy parties as she was so gentle & calm quite unusual for a Harlie.
My friend who has dobes has a bitch that has a problem with other dogs if they get too close due to a couple of dogs in the park having a go at her however she is fine with my cavaliers & will even try to follow them into their crate at shows(it is big enough for her as well)