I found it, in one of the "Chicken Keeping Secrets" newsletter. Here's a pasted copy of the part about when to start turning eggs:
"If you set the eggs in the morning, count this as day 1, if you
set the eggs late in the day or in the evening, count this as day
0 and tomorrow as day 1.
In either case, once you have set the eggs, do not touch them for
the first day.
The developing chicks are most delicate at the beginning and the
end of the incubation period.
Beginning on day 2, you must turn the eggs 3 to 5 times each day.
Try to keep regular, frequent intervals. Turn the eggs either ¼
or ½ way round each time."
I don't know how accurate this is, so I'm hoping there will be some folks here who've tried this method. I have a bunch of beautiful shipped Delaware eggs I'm about to set, I really want to be careful with them.
I've had good and bad hatches in the past, I'm trying to make sure this one's good!