Mine tend to lay between 7 and 10am during the summer, but it can be later in the winter due to the darker mornings and if they are going into moult. I normally search about 9am and the hens can get used to you popping your head in so they don't seem to disturb much. If they've been on the nest for over half an hour I do have a quick check underneath them and have removed a few eggs that way to stop them going broody.