
I prefer the slightly larger chip from TSC or any feed/country/farm store. Cheaper, by far, than the small "pet" packages at generic stores.
I use them from day one. The more "sawdust" type, finely ground stuff is too confusing to them and having the chicks eat the powdery stuff is a risk. Won't kill them, per se, but it obviously lacks any nutrients and fills them with raw fiber. Chicks under broody hens, in the natural, have straw, or pine needles; nothing fancy.