Ours lay eggs starting after 9 AM, but none after 3:30 or so.
Hens may sometimes not use the nestbox right away, because when they start to lay eggs, they don't really know what's happening.
But to get your hens to use the nestbox, put some fake eggs or golf balls in there, and they will start to get the idea.
If your hens are free-range, they may find other places they like more than your nestbox, so maybe keep them penned up the first few weeks they lay so they get used to using the nestbox.