I have the same issue, and this is my first time as well, so I am just sharing what my experience has been. My three little mutts where born on the 20th of December. I never had them separate from the rest of the flock, but I did provide the mama with a large cat carrier which she stayed in for the first few days with a heat lamp pointed on it. After the first three days or so she and the babies have been sitting under the lamp right outside the carrier. The other chickens leave them alone. I have a SLW that is an "aunt". She sat with the mama broody a lot while she was brooding, and my broody will let her around the babies. The others just ignore them, or, if they try to eat the chick crumbles I have in there, the mama pecks them in the head.
Just recently the mama has been coming out of the coop for short periods of time. Especially when I throw treats out. The babies will come to the door, but so far have not tried to go for the ramp. What happens is, the mama runs out, grabs a bite, hears the babies crying for her, and runs back up. If they get near the door she runs up and shoos them back in.
With my original group, (whom I got as day olds) I put them in the coop around 3 weeks or so, and they were able to navigate the ramp at that time, and I have a pretty long and steep ramp. Here are some pictures.
Here are my original girls navigating the ramp last summer:
Here are my current little lovelies and their set up:
Remember, every coop dynamic is different. You have to judge how your chickens will react to the babies. And also how protective your mama is before you let everyone interact. All it takes is one overly aggressive hen (or roo) and there could be tragedy in the coop. Hope this helps a little. Like I said, I am far from an expert, but I always think it helps to hear how someone with a similar situation is dealing with it.