Actually, there's no set time of day that a chicken lays an egg. It depends entirely on the chicken. I've kept a calendar on my girls since they were little.
The EE laid at 20 weeks, 5 days. The first RIR laid at 23 weeks, 6 days. The last RIR laid at 27 weeks.
The EE's eggs are the smallest, the last RIR's the largest. In each of their first year of laying, the EE laid 245 eggs, the RIRs 307 and 301 eggs.
At nearly 2 1/4 years old, I'm still getting between 14 - 17 eggs a week from the 3 of them. The EE lays 2 - 3 days in a row and rarely lays an egg past 1 in the afternoon. RIR2 lays 3 - 5 days in a row and rarely lays past 2 in the afternoon. RIR1 will lay as late as 4 pm and lays 4 - 6 days in a row. When they skip a day, their next egg is laid fairly early in the day, then they lay later in the day each day until they hit their individual time when they won't lay beyond. Then they skip a day and start all over again.
It's kind of fun watching their little patterns. Knowing their patterns helps me know when it's safe to let them out for the day. If I know I'm expecting a couple of early layers, I'll wait to let them out. Otherwise, I just listen for them to make their "I need to lay an egg" whine and I walk the whiner back to the coop. I'm not sure who has who trained.