Hesiod - Works and Days - Sound Advice
Type of Spiritual Experience
This is the Days bit of the Works and Days .
I'm not sure how one avoids a day - he says to miss the 5th day of the month out, but unfortunately no hints or guidelines on how.
But remember to beget on the ninth, luckily he does not expressly state that one should not beget on other days, so apart from the 5th it could be a good month for all of us.............
I'm joking, but I suspect this was hidden symbolism.
A description of the experience
Hesiod: Works And Days - translated by Hugh G. Evelyn-White 
(ll. 746-747) When you are building a house, do not leave it rough-hewn, or a cawing crow may settle on it and croak [I think he means croak as in noise, not croak as in die - ie croak it].
(ll. 748-749) Take nothing to eat or to wash with from uncharmed pots, for in them there is mischief.
(ll. 802-804) Avoid fifth days: they are unkindly and terrible.
(ll. 810-813) The ninth of the mid-month improves towards evening; but the first ninth of all is quite harmless for men. It is a good day on which to beget or to be born, both for a male and a female: it is never an wholly evil day.
(ll. 819-821) On the fourth day open a jar. The fourth of the mid-month is a day holy above all. And again, few men know that the fourth day after the twentieth is best while it is morning: towards evening it is less good.
(ll. 822-828) These days are a great blessing to men on earth; but the rest are changeable, luckless, and bring nothing. Everyone praises a different day but few know their nature. Sometimes a day is a stepmother, sometimes a mother.