It's random. Completely. But it DOES depend on the individual hen. I have one hen who lays every day before noon. Hasn't changed in over 18 months of laying. She will skip a day or two, but it's still before noon when she lays.
I have another that is so incredibly random as to when she lays, I can't pin it down at all. Sometimes it will be first thing in the morning, sometimes it's the last thing she does before roosting. And the days can't be tracked either. Sometimes she'll skip a day. Sometimes she will actually lay two in one day. Sometimes she skips a week (but she'll still lay year-round).
I also have one strange bantam that always lays her eggs after dark. That's a new one to me! I've never known a chicken to lay during roosting hours AT ALL! Chickens have great vision, but not at night. Their night vision is worse than any human. So laying during those hours is incredibly strange!
So it will depend on the hen, but there is no standard for the various breeds either. They will lay whenever they lay.
Also to go back on other content in this thread, and as others have said, locking hens in a coop won't help them lay in their proper nest. They may not lay at all, or they could even just put it on the floor of the coop. The best way to show a chicken where to lay, is to put an egg (or something similar) where you want her to lay. Chickens want to lay their eggs where there are already eggs being laid. They're a bit on the naive side, and think that round object is the egg they already laid - even if it's from another chicken, or not an egg at all, and even if they are laying their very first egg ever! This is how they "gather" eggs to sit on later. They find existing eggs, assume it is their own, and lay more in that same spot until they have enough to sit on.
If you want to get as real as possible, use an egg from your refrigerator that was purchased at the grocery store. Let it warm up to room temperature, and then set it in their nest. It may start to smell bad after a while (takes about a week at least), but your chicken won't mind. And if you have white egg-layers, mark it with an X using a black marker, so you know which one isn't good when you collect the eggs later on.
If you don't want to go that route but you have extra cash, try ordering some fake wooden or ceramic eggs from McMurray or Meyer's hatcheries. If you want cheap but fake, try golfballs (I use golfballs to entice my broody hens to start sitting). But there is no way of forcing a chicken to lay before she's ready, no matter what you do.