Jinley was just under 11 weeks, mainly due to a wedding we had to go to. The breeder did not want her to go before 10 weeks, so it was only an extra week. She was kept outside in a pen with her mom as she was the last to go, had had no other socialisation - not even been in a garden. But in my opinion I was glad about this, her first real outside world experiences were with me so I could control the situation and the outcome.
Like others have said, find out what the breeder will be doing with her - eg daily grooming, handling, even starting on early re-call. Personally I wouldnt worry too much about toilet training or sleeping through the night as this would be disrupted when going to a new home anyway.
If I couldnt have had her for an extra couple of weeks, I would have still waited.
Hope this helps.
Pat