(Quote) Does this clarify things for you? Also of note; the 7th day of each month was (apparently) sacred to Apollo. Since one of the aspects of that God was Apollo Epicurius, is it too bold to propose that Neocles and Chaerestrate may have had this in mind when they named him? Or perhaps Epicurus really was born on the 10th or 20th, and later ancient commentators pigeonholed him into the seventh to fit the Apollo connection. Impossible to say. But I would like to see this "3 tenths" business cl…
One further point I'm gleaning from Wikipedia; the Greeks celebrated birthdays monthly instead of annually. So we've got a local Athenian calendar, enshrouded in a Greek culture, which has been generally interpreted for us by non-Athenians, non-Greeks, and/or latecomers.