Same here, I brood mine on sand and dirt (all the grit a chick could want) and start feeding greens, small sprouts, small feeder insects from a couple of days old on.I start by adding chick grit to the chick starter and after a few days with grit I start on the "finer" sprouts. I do this as soon as everybody is hatched and they are in the brooder. I have never had a problem with green poop.
Good luck and do what works for you.