My coop and run should be ready in about 3 weeks so I'm wondering if I should buy all day old chicks or if i should start with a few mature birds and then add a few young ones?
Any help is appreciated!
The learning curve is more gentle with pullets, as opposed to chicks (and less demanding). As Rod-T suggests, getting a hold of point-of-lay pullets (those that are almost at laying age - say 4-6 months) is a great option, rather than buying hens that are already laying (since its difficult to tell exactly how old they are).
You'll soon want more chickens, and after a while building up your experience with the pullets, it will make the move to raising chicks that much easier and successful.