In fact:

Although your new puppy might have lots of other dogs to play with at home it doesn’t count as socialization. The other dogs at home count as ‘family’ not ‘friends’. Proper socialization has to happen outside the home. Puppies need to meet other dogs especially to learn that other dogs are dogs. Because dogs comes in so many different shapes, sizes and varieties; dogs does not instantly recognize other dogs as dogs until they had a chance to interact or see many different types before they can know this. That is why it’s so important that interactions with other dogs are good and positive (especially when they are younger than 4 months old) otherwise dogs might start to get an aversion to other dogs if most of their interactions with other dogs are negative.

Secondly, a misconception:

‘Socialization is dogs playing wildly off lead with a whole lot of other dogs.’

In fact:

Socialization does not have to be done off lead. It also does not have to be dogs playing wildly with each other, in fact there are so much that can go wrong with this and is not a good idea unless you know the dog/dogs your dog will be playing with. 

1stly, when dogs play off lead you, as the owner, does not have any control over your dog or a situation if one should arrive as they are normally a distance away from you.

2ndly, when dogs play and run off lead they tend to get very excited and most dogs go over their threshold when they get excited and cannot control themselves anymore. The chances of something going wrong with dogs over their thresholds are very good!

3rdly, if you allow your dog to run with dogs you don’t know you also don’t know if they have been properly socialized, have been taught proper frustration levels and can stay under their threshold appropriately. 

4thly, most dog owners does not have a strong or 100% recall with their dogs and cannot get their dogs back if they need to!!

Thirdly, a misconception:

‘I can socialize my dog at any age. Later on when I have more time I will socialize my dog and start with training’

In fact:

One can start with training at any age in your dog’s life but it’s not the same with socialization. A dog has only one period in his/her life to be socialized and that is very early on in your puppy’s life. The only socialization period in a dog’s life is from 6 weeks until (at the very latest) 4 months of age. The socialization phase for a dog then closes and there is no do over after that. One cannot re–socialize a dog after 4 months. If your puppy has not been socialized before 4 months of age one can teach a dog to be around other dogs but this is not the same as socialization.