Most breeders will not let puppies leave until they are 12 weeks old so I would say 14 weeks is a good age, they will have had time to ween and socialize with their litter mates. The younger the puppy, the more work and more supervision it takes. I took a month off work when I got Lady at 8 weeks old (and my breeder didn't let most leave that early, only because I was experienced with dogs and had the time off work).
Lady (1.5 year old tricolour) & Gracie (4 year old blenheim)
"Happiness is a warm puppy" - Charles M. Schulz