I think its a good thing.
I got my last dog at 6 and a half weeks old. The same day I took him to my friends house who was also a dog trainer. I took him out and about with me immediately after his first injection (just did not let him sniff around too much). I reasoned that because I had other dogs who were coming and going and carrying anything/everything in on their feet that he could not catch anything they had not brought in anyway! He started at the normal training class (with adult dogs) when he was around 7/8 weeks old.
Guide Dogs for the Blind send their pups to the puppy walkers aged 6 weeks, and that is the optimum time for the pups to go to their new homes and start socialisation.
You may find this article useful:
Puppy Socialisation and Habituation (Part 1) Why is it Necessary? | Association of Pet Behaviour Counsellors
Taken from above:
" Guide Dogs for the Blind, who, until 1956, used to rely on the donation of adult dogs which they took on approval to maintain their training stock. The success rate of these dogs fluctuated between 9 and 11 percent and it was recognised that this could be improved if the association could supervise the rearing of puppies. These were purchased and placed in private homes at between ten and twelve weeks old or even later. Things improved, but the results were not good enough. It was Derek Freeman, who pushed to have puppies placed in private homes at an earlier age to optimise socialisation and habituation during the critical development period. Derek had a strong belief in Scott and Fuller’s work and importance of early socialisation and habituation in the production of dogs that were best able to survive and perform in the world at large.
Derek found that six weeks was the best time to place puppies in private homes; any later critically reduced the time left before the puppies reached twelve weeks; but if puppies were removed from their dam and litter mates before six weeks they missed the opportunity to be properly socialised with their own kind, which resulted in inept interactions with other dogs in later life. The training success rate soared because of this policy, which was carried out in conjunction with the management of the gene pool via the breeding scheme Derek also pioneered. Annual success rates in excess of 75 percent became common. You might think that this is a special scheme for dogs with a special function. In fact, what the scheme provides is adult dogs with sound temperaments. These dogs coincidentally make the best material for guide dog training which does not start until they have been assessed at ten months or older."
Sue