I'm certainly no expert, but I got my Sadie when she was about 8 weeks old. She was amazing even then, and continues to be so now in my humble opinion.
For the trip home, she traveled in her crate for a 5 hour drive from hell from northern San Diego County through LA traffic back up here to "Sort Of Southern California" without a sound. We only stopped once to air her...she slept quietly the rest of the time. To this day, she's comfortable with road trips of 8-10 hours a day for at least two consecutive days (stopping to air a couple of times en route).
IMHO, the bonding that happens with getting your pup as soon as possible is critical. It also gives you an opportunity to start with training games when the pup is still young enough not to have developed (or started to develop) bad habits. My girl has been an incredible family member, and is also a focused, responsive "machine" in the field. I don't what more I/we could ask for.
So: when is the best time to get a pup? ANYTIME, I say (gotta love those puppies!)...but for us the approximately 8 week old age was perfect. It seems to work out best for both of you in the short term and the long term, as well.