If the breeder is giving you the ran-around, you did not choose the right breeder. A good breeder keeps precise records of all the babies, hatch date, parents, leg band number, health notes, etc.
This is a 4 week old baby:

These are 8 week old (I couldn't find any at 6 weeks)

But, babies size, plumage, level of energy, coordination, etc also depends greatly on the health of the parents, what they were fed before and during breeding and what formula the breeder used for hand-feeding. Babies from semi-depleted birds that were not fed properly will look scrawnier, smaller, with sparse and slow growing plumage, not as coordinated, etc.
Do you have experience hand-feeding and weaning babies? Because raising a hatchling properly is not as easy as some people make it seem... It's not only time consuming and labor intensive (you can't go anywhere for weeks, have to get up in the middle of the night to feed, have to weight and sterilize daily, etc. etc) aside from the dangers of aspiration, sour crop, crop burn, etc