Chickens are both predictable and fickle.
The rule of thumb is they lay an egg every 25 hours, but different
breeds and for that matter different individuals within a breed have
their own schedule typically 25-30 hours. I have some hens who are early
morning layers and I have some who wouldn't be caught in a nest box
before 10am. At the other end of the day they generally stop laying for
the day within 2 hours before roost up for the night. This is where
then whole thing about using artificial light comes in to play in the
winter time to "lengthen" the "laying day". Just stating that point to
give you insight into the biology involved, please not to open the
debate about the pros and cons of using lights in a timer in the winter
time :-) Deal..I won't.
Lets look at a hypothetical chicken schedule. lets say your hen has a
26 hour clock and lays her first egg in her "new" cycle at 9 AM on
Monday , Tuesday she will lay at 11AM, Wednesday at 1PM and Thursday at
3PM ...On Friday you might expect her to lay at 5PM but since this is
getting close to roost up a 6:30PM ..she will hold off and lay instead
at 9AM on Saturday.starting the next cycle. Ahh that explains why I
thought for a while the time was reversing.
Too some degree the hens can decide to hold on to the eggs for any
number of reasons thus delaying and moving the whole schedule to the
right. Let say Henny-Penny is sitting in the nest box at 2:30 pm
thinking about her 3 PM egg when you walk in to do some chores in the
coop..She gets all agitated by your presence, jumps down and runs
outside skipping her 3 PM egg and holding on to it till 9AM the next
day. If I had disturbed Henny-Penny at an 11AM laying she will likely
come back and lay the egg later the same day ( say noon ), her 26 hour
clock is reset by the act of laying the egg and tomorrow she will lay at
Pullets are less predictable to be sure and it takes months for their
schedules to settle in. As I said the cycle time varies from individual
to individuation. You can set a watch by my Australorps who are 25 hour
layers. I have one Americauna who has a 30 hour cycle, and I have a 3
year Buff Orpington with a 27 hour clock who lays 4oz eggs that it
hurts to look at. She lays for a week or two then takes a month break
...lays for another two weeks and takes a break ... I guess I would too,
it cant be any fun for a 7lb hen to be laying eggs the size of goose eggs.
So the only constant is the "no laying 2 hours before roost time" rule
which also gets earlier as the days shorten.
^the above was copy/pasted - tyvm to the chick who typed it out! ;)