When do EE's lay eggs?

[chickiechica]

Mine just started and is 18.5 wks with green eggs. I have noticed that the food consumption has really gone up and she is all about the treats, even waiting at the sliding glass door for me to come out. They are eating like crazy! About a two weeks prior to her laying she started 'squatting' when I went to pet her. One of my others is doing the same too and another is just starting...Of course then there's the New Hampshire, who isn't at all.