I used to routinely release my puppies at 8 weeks. I didnt have any problems.
But after some professional breeder advice and some reading on my own, I decided to routinely keep them longer 10-12 weeks.
My last litter I did release a puppy at 8 weeks to a couple who lives 15 minutes from me. They had lost their dog of many yrs were devastated and begged to go ahead and take her home. The puppy was a spunky social butt and the lady stayed at home so I went ahead and released her. SHe is doing great, and they didnt have a problem.
But Keeping a puppy longer is better I think. I think it true it puts the finishing touches on them. (for socialization mainly) Makes them more confident.