I separate the mom and chicks for at least 3-4 weeks. We have a "coop within the coop" so that everybody can see each other. It'll also depend on how protective the new mother is too. So far I've had good luck with my bantams. Two out of the three mothers have been VERY protective. The rest of the flock (1 rooster and 6 hens) give them plenty of room when we do integrate them. The "dud" mother didn't care about her chick. Luckily the little fellow had the sense to stick close to her until he got some size. Plus, he was much faster than any of the other flock members.
The protective mothers will fluff their feathers up like turkeys and spread out their wings as a warning. They will get between whatever (human or fowl) and their chicks. I've decided for future hatching, I'll only allow the proven protective hens to set on eggs. Good luck with your chickens.