How can I tell when the hens are about ready to start laying?

[Dayrel]

My oldest, a Barred Rock, has been squatting for two weeks now. Still waiting for that first egg. Sigh...

 

[chickengeorgeto]

A pullet that's near lay will check out their nest boxes, squat when hovered over and may sing the egg song. A laying pullet will do all the above and have a larger wet vent.

ETA: Oh, and a pullet near lay will have a large deep red comb & wattles.

A large, deep red, comb is both the most common as well as the easiest thing to look for.
A hen or pullet about to begin or resume laying will have a comb, waddles, and especially a face that looks like a very ripe strawberry, complete with little bumps that resemble the seeds of the strawberry. Remember that only healthy, well nourished, hens lay and pretty much from the first egg that she lays her head gear starts going down hill.
Some of you may not like what I am about to say but that doesn't change the facts. Hens lay eggs for us in response to our fooling them into thinking that every egg that they lay will become a baby chick. In other words hens lay because they believe that the conditions are right to produce offsprings. They definitely don't lay so that we can enjoy mayonnaise on our tuna fish sandwiches.

 

[barred2rock]

My oldest, a Barred Rock, has been squatting for two weeks now. Still waiting for that first egg. Sigh...

My most mature was squating for about a month before actually laying. Almost two weeks later I got two (intact) eggs instead of one today. Although someone layed rubber eggs four days in a row then stopped.

Edited: typos (sorry, dinner was ready; typed too fast).