12 weeks is best for the pup. If your breeder is in Florida, it is illegal for them to sell the pup before 8 weeks of age, so you are dealing with someone who either doesn't know their business or is purposely a law breaker. Not a breeder I would want to deal with.
Here is a table with the legal age to sell a puppy, I had a hard time getting the page to open, so you might have to try a few times:
Age to Sell Puppy Table