Hi there,
Going by the pictures you provided they don't look quite ready to lay yet. My Orpies were around the 24/25 week mark when they started laying, and I've heard of some that go all the way to 28/29 weeks without laying a single egg!
Generally speaking, your birds will probably develop bright red faces, combs and wattles before laying. Their combs and wattles will also plump out a bit. My girls never did the squat, but if they start doing it that is also a good sign.
I would start making up some nice nesting boxes for them now though. They will start to show interest in them, jumping in and out and flicking hay everywhere, trying to make them look homely!
There's not much you can do to hurry them along unfortunately, and having just gone through this myself I understand the wait is sooooo hard!
They will lay when they are ready though. Good luck, and I hope that is sooner rather than later for you.
Krista