They can lay at any time of day. Most seem to lean toward the earlier part of the day I have found but there are some who will wait until afternoon. Each hen is different.
Well the books say it takes 25 hours for an egg cycle. So if your hen laid an egg at 8 am next day should be @ 9 am. Mine kinda lay on that schedual. Not always. I have gotten an egg here as late as 6 pm. If they get disturbed on the nest it can take a little longer than 25 hour. And having said all of that. The chickens don't always read the book. Hope that helped a little.
The majority of my chickens lay in the early afternoon or evening - just to be different I guess.
The one hen I would like to re-train always waits till it's almost dark to go to the nest box. I literally stand at the door and wait for her to get finished so I can shut them up for the night.
Edited for spelling, goodness I'm tired.
We've got a couple that lay first thing in the am, then the majority lay by 1:00, and finally a couple lay in the late afternoon. Usually, they are all done by 5:00.