laying eggs in the run

Hi everyone, So excited about this new adventure....alot to learn. I have 8 girls and 1 rooster. They started laying a few weeks ago. I don't think they are all laying yet b/c I occasionally get a tiny one, so I assume that's when someone new begins to lay. I have 4 nesting boxes all in a row separated by my entry door. They are off the ground with 2 on either side of the door. The first few eggs were found in the last box and the 1st box. Now on a regular basis there are 3-4 eggs in the first box, 1-2 in the 4th box and occasionally 1 in the 2nd box. I have never seen any in the 3rd box, but the hay is worked down in that box. Today I found 2 eggs in 2 different places in their run. I had put some large river rocks in the run under their water to keep it from puddling and I wonder if they think they are eggs and are now laying by them. But they look different than the ones I've been getting so it may be a new layer.

Also, I haven't clipped their wings, is it too late to do that is they are about 18 weeks old? And how do I do that?

Thanks in advance!

Putting some fake eggs/golf balls in the nests can help entice them to lay there.
But it can take up to month or so for things to smooth out, finding eggs every where but the nest is not unusual at first, but they'll catch on soon.