You'll get different opinions on grit. Many people do not give their chicks grit in the brooder as the prepared food can be digested without being ground up in the gizzard. And if they are free-ranging on ground that has sand and small gravel, they will probably get enough there.
My personal philosophy is to offer grit in a separate dish or feeder after day two. I want them to spend the first two days figuring out what their main food is. Granted, the prepared chick feed does not require it, but what if a hard-shelled bug wanders into their brooder or they ingest something that needs to be ground up to pass through their system. Maybe I'll want to give them a treat that should be ground up in the gizzard. I figure you cannot go wrong offering grit but you might go wrong not offering grit.
As I said, my personal philosophy. Many people are successful not offering grit.