Hi,
Thanks for all your brill advice! Just wondering what is the minimum age you should get chicks and is 6 week too early? Thank you!
Do you have a brooder? That is, a smallish draft-free place where you hang heat lights until chicks are fully feathered? If so, then you can get day-old birds easily.
If you do not have a brooder/don't want to deal with chicks, then as soon as the chicks are fully feathered (including their heads) they can take any temperature and will be fine in a run as long as they have a place to get out of the wind and rain. Feathering speed is dependent on the breed a bit as well as on the temperature where the chicks were kept, but is usually complete by six weeks.
If you're getting older birds anyway, I would personally pay for "started pullets" that will be around 18 weeks old. You'll start getting eggs between 18 and 30 weeks, depending on the breed of the chicken.