My flock will be five weeks old tomorrow. Only one, the Cinnamon Queen (and the alpha for sure) is clucking at all and she just started. Most of the time she peeps, but if she gets ruffled she will let out with a soft "BOCKabarglebargle" noise. Then back to peeping.
Mine started around 6 weeks old and they are 12 weeks now and that is all they do. I do have one younger baby that is about 4 weeks and she is starting to now I think she is just copying what she hears.