Both of my barred rocks laid right around 21.5 weeks. Bonnie and Charlie both had nice red combs for a few weeks prior to them laying. Then in the 2 or so days prior to laying the first egg they were bock bock bocking for hours!
I wonder why yours are taking so long - tell them to step it up and warn them they are a dual purpose breed - haha
chickens are like any other creature they will lay when its time and probably when you least expect it some lay sooner and some later.
I would keep feeding them laying mash/crumbles make sure they are not stressed. I purchased some 8 weeks old chicks on June 4th for my birthday
an easter egger,barred rock,silver laced,gold laced and a buff none has started laying but I do see their maturity starting to show through just be patient and spoil them rotten and soon you will be paid back with beautiful eggs!
When they start laying those yellow legs and feet will start to fade, bleach out a bit... So if they start and hide eggs from you (sorry don't know ur set up, free range or cooped) but I've had some hide nests in the woods, and notice their legs changing color, so I went exploring and found a couple of hiding spots where eggs had been (***** got to them before I did). Then I took them to the nest boxes and they laid regularly there. I think they were free ranging and "got the urge" and laid the first egg there and kept going back cuz that's what they thought they were supposed to do ! Hope you get cackle berries soon and hope this may help ya, or someone that reads it !