
Hi guest,
Yes, they certainly have an individual personality by 6 weeks! The breeder should have been able to recognise each one by their behaviour and attitudes from about 4 weeks, so should be able to guide you towards the right puppy for you.
There are many things to be borne in mind when you're choosing a puppy, whether it's to be purely a companion, or destined for the showring as well. For any pup, make sure that both parents have had all the relevant health checks, and make sure you get to see the certificates proving this.
Assuming here that you are after a family pet, often the most suitable pet pup is the second or third to come and say hello to you. Avoid the shy one who cowers away, and also the bold pup who is all over you immediately - these can both make marvellous dogs, but aren't necessarily the best for novice owners.
And make sure you like the look of it! A pup who has a feature that you aren't too keen on when it is cute and tiny ("wrong" colour etc) will never really capture your heart.
Hope this helps. :)