I think it depends on the chicken... mine have been laying for over a year now and sometimes they lay in the morning, sometimes in the middle of the day, and sometimes in the evening. I haven't noticed the same chicken in the nest box at the same time each day. I also have a few that go in lay an egg and are out back in the run in no time and a few others that like to 'sit' on the nest for hours before they lay... I guess each chicken has their own way.
I do remember that for the first few weeks that they started laying that there was no consistency with when or how often they laid an egg... some were giving me an egg a day for 3-4 days and then nothing for 2 days, others were laying every 2-3 days. I had 8 chickens to start with and when they all 'regulated' their egg laying, I was getting 5-6 eggs a day. Now I have 11 hens, 2 roo's, and 3 ducks. My first flock seems to have taken a break and I'm only getting about 3 eggs a day, but I'm on egg watch as I hope that 4 more hens should start laying soon, I hope. I also remember that my girls didn't sing an egg song for a few months until after they started laying - maybe they were still in shock that they laid an egg and didn't want the other girls to know, now I can hear them in the house as they are louder than the roo's.
Enjoy your eggs, I find it amazing that these girls figure it out all on their own.