HI, welcome! IMO, grit is essential. When I start chicks, I give them grit shortly after they have started eating and drinking well. After the first day or two, when they are filling their crops and eating well, I give them a plug of sod from my yard. This gives them: first grit, minerals, first greens, perhaps a few insects, seeds, and worms. First experience "scratching" for their grub, first dust bath and LOTS of play value. That soil will also load their guts with beneficial bacteria and fungi to jump start their gut flora and their immune systems. That soil will also give them their first exposure to the pathogens they will encounter in your yard. This is a GOOD thing. They need that exposure during the first 2 weeks of their lives, while they still have antibodies received (while still in the egg) from their mother!
If you have a gravel driveway, you can also scoop some gravel up for them. They should be able to pick out the sizes of grit that they need from that. Don't get your gravel from the side of the road. Too many contaminants there.
Don't put grit in the chick's feed. Serve it up separately.
While you are researching, I do hope you will look at your brooder options: A heating pad brooder is much safer, more economical and comes as close as possible to resembling the type of heat supplied by a broody hen. (compared to a heat lamp.) Do a thread search for Mother Heating pad in the brooder.
@Blooie has 2 wonderful articles and a thread dedicated to the subject. Also, you can provide a nice big brooder by picking up an appliance box. By the time your chicks are 2 - 3 weeks old, they will need 2 s.f./chick!!!