Don't forget to quartine your new layers.
I always integrate my newbies, after the quartine period is up, when it's dark and the others are roosting in the coop. It seems to throw everybody for a loop when they wake up in the morning. I haven't had any problems doing this and yes, they do go through the normal pecking order. I have integrated a rooster, laying hen and a pullet this way.
The pullet I hatched myself and she still thinks she is a dog seeing that she has been around humans for the first 16 weeks of life. I integrated her last weekend and she is slowly coming around to the flock. She won't follow them around yet, but will mingle with them in the barn were she hangs out during the day. Then, she waits until the flock is settled in the coop before she ventures over herself to roost.