I don't know how much calcium that product has in it. I see that calcium carbonate is listed as an ingredient, so I would be concerned. Too much calcium can cause bone deformations or kidney damage in growing chicks.
You can use coarse sand as grit. Don't use that fine smooth play sand. That is too small to work but look for rough irregular-shaped grains of sand, like construction sand. For my chicks in a brooder, I go to my gravel driveway and scrape up some finer pieces. If your roads were salted due to ice, this may not be a good idea. Chickens cannot handle a lot of salt.
I usually give mine grit the second or third day in ther brooder. As long as all they eat is prepared chick starter, they really don't have to have it, but I think it starts their system operating the way it is intended to. I just put it in a separate small plastic yogurt cup wired to the side of the brooder. I wait until they know what their main food source is and I don't give them a lot to where they can pig out on it.
You can start giving them treats any time after they have grit. I usually don't that much, not because of any reason not to, I just don't. But mine are prepared for the next time my wife stuns a wasp and puts it in the brooder to watch them play keepaway, or a bug wanders in their brooder, or if they eat something they need to grind up to pass through their system, like larger chunks of wood shavings.
Good luck!