Pecking order set-up starts from day one in the brooder. It should be up and running fine by the time they are six to eight weeks old. If it is running smoothly, chances are you won't even notice it. Everyone knows their place and as long as no one gets bold ideas about moving up the totem pole, there won't be fussing.
I'm not noticing anyone pecking anyone or anything, except for when we brought them home, one of them was pecking everyone's head. But I read that they don't have a pecking order until 6 weeks. We do watch them pretty close, but the one was pecking everyone is usually the one who is pushed back or blocked when we set mealworms out on a plate. She is also currently one of the smallest. (two of them are small, and two of them are big.)
From the book Chickens: Tending a Small-Scale Flock for Pleasure and Profit by Susan Weaver - In any flock of chickens, there are birds who peck at other flock members and birds who submit to other flock members. This order creates a hierarchical chain in which each chicken has a place. The rank of the chicken is dependant upon whom he pecks at and whom he submits to. He ranks lower than those he submits to and higher than those he pecks at. A flock of chicks generally has their pecking order up and running by the time they're five to seven weeks old. Pullets and cockerels maintain seperate pecking orders within the same flock, as do hens and adult roosters. Hens automatically accept higher-ranking roosters as superiors, but dominant hens give low-ranking cocks and uppity young cockerels a very hard time.
In a closed flock with an established pecking order, there is very little infighting. Each chicken knows his or her place, and except among some roosters, there is suprisingly little jostling for position. Dominant chickens signal their superiority by raising their heads and tails and glaring at subordinates, who submit by crouching, tilting their heads to one side, and gazing away - or beating a hasty retreat.
The addition of a single newcomer or removal of a high-ranking cock or hen upsets the hierachy and a great deal of mayhem erupts until a new pecking order evolves.
i didn't really notice the pecking order with out first or second batch of chicks, but the batch we have now has 20, and they all range from very different ages and breeds. (about 9 weeks to 2 weeks) they all get along really well, but i do see some pecking order going on even with the 3 week olds. you'll notice the more timid ones being toward the bottom and the more aggressive, assertive, and adventurous ones toward the top. our 9 week old cockerel and our older pullet (both rescues) are at the top and act kind of like mommy and daddy to everyone, they keep everyone in line. it's really cute, actually.
So, let's say a chick is a bit adventurous, struggles when you hold her, is one of the biggest, and usually gets the most mealworms. Does that make her at least in a higher position? (There's two that steal more mealworms.)