If your free ranging you don't have to worry about grit. They will pick up what they need naturally, but if you keep then penned then you have to provide grit.
If your feeding commercial starter, you don't have to give grit. Everything they need is in there. I've read on here that if you give treats, such as yogurt, you need to give additional grit, but I'm not sure about that.
I do give mashed boiled yolks with my first feedings and I know I...