The Deipnon (Hene kai Nea)--or Hekate's Deipnon--is celebrated any time before the first sliver of the new moon is visible. In practice, this is the day after the new moon. The Noumenia is held the day after that, when the moon has become visible again, and Agathós Daímōn the day after that. It is important to note that the ancient Hellens started a new day at sundown the day before. Instead of starting a new day at midnight--or in the morning--like we do today, they started it at sundown of the previous day. This means that--when applied to modern practice--the Deipnon starts on the day of the suspected new moon, and the rest follows after, to the total of four days. Confused yet? How about a schematic. In this example, we'll assume that the sun goes down at six P.M. on all days.
All day - (suspected) new moon
6 P.M. - start of the Deipnon (Deipnon night)
All day - day after the new moon
6 P.M. day 1 to 6 P.M. day 2 - Deipnon (Deipnon day)
6 P.M. - start of the Noumenia (Noumenia night)
All day - second day after the new moon
6 P.M. day 2 to 6 P.M. day 3 - Noumenia (Noumenia day)
6 P.M. - start of Agathós Daímōn (Agathós Daímōn night)
All day - third day after the new moon
6 P.M. day 3 to 6 P.M. day 4 - Agathós Daímōn (Agathós Daímōn day)
This difference in perception is especially prudent when you--like I--feel the need to celebrate the ritualistic part of the Deipnon and Noumenia at night. It means that I can't hold my night time celebration of the Deipnon on the day of the Deipnon (day 2 in the schematic), but need to do it the day before the day of the Deipnon (so on day one, after 6 P.M. in the schematic).
Hekate’s Deipnon is the traditional time to end the old month and prepare for the new one. In ancient Hellas, the Deipnon was celebrated with a Supper for the Titan Hekate--made up of leek, egg, cakes, fish, unions and garlic--and set out at the outside shrine to Hekate, and then placed at a crossroads as an offering to Her--Hekate Trioditis, Goddess of Crossroads--and the vengeful spirits who were in her following. In addition to placation, the Deipnon is also a time of purification; in ancient times, a dog was taken in, touched by all members of the oikos so any lingering miasma was transfered to the dog. The dog was then sacrificed in a holókaustos. This was most likely not a monthly thing, but only performed when the household was troubled. As Hekate's sacred animal is a dog, the sacrifice also served to regain, or keep, Hekate's favor upon the household. The house was also thoroughly cleaned so the new month could start fresh the day after. Debts were repaid on this day.
Of course, I'm not going to sacrifice a dog. For one, it is against the law to do so, and my girlfriend would leave me the second I tried. She still won't watch Beethoven because--apparently--the dog gets mistreated somewhere along the way. Anyway... my Deipnon celebration is as follows: at sundown (as per a wonderful Google Calendar), I gather the Supper and place it at the shrine to Hekate with Her Hymn (Orphic Hymn 1 (or 0)). I then go about collecting the remnants of sacrifices I have made in the month past--most of which I have already collected in an urn under my main shrine at the start of every new day--from my various shrines. Then, I set the bowl on the ground in front of my main shrine, throw barley into it, purify myself with khernips and add ethanol to the offering. While reciting the Orphic hymn to Hekate, I place a previously fabricated wax dog figurine onto the pile of left-over offerings, and light the sacrifice with fire from Hestia's candle. I then take the offering outside where I leave it to burn itself out. The dog will have melted away--taking the impurity of the household with it--and I let the offerings cool down before collecting them in a jar.
With the last daylight, I take the burned offerings, the Supper, wine, a banana-leaf plate (because it degrades very easily, a requirement because you don't get to take the plate home), and a special sacrifice (usually incense or lavender) to the 'crossroads' outside my house, where the garden meets with the street. I recite Hekate's hymn again, and add prayers to take the old, the shame-filled, the impure out of the home, as I have taken these offerings out of the home. Then I pour a hansom libation of undiluted wine on the ground near my offering and turn around, walk away, and do not--I repeat, do not--look back, as it is said we will take the impurity--as well as a slew of vengeful spirits--back home if we do. I make sure to be inside before dark, and try not to go out again if I can help it.
Once home, I empty my kathiskos, and clean my ritual tools and shrines. The next day is all about cleaning. I do laundry, dishes, vacuuming, mopping, etc. I also pay any bills left unpaid, as well as get all those odd jobs and chores done I've been avoiding this month. I try to get one major cleaning or sorting project done on the Deipnon; clean the oven, the cupboards, etc. I offer a hymn (Orphic Hymn 8 or Homeric Hymn 32), something sweet like cakes and/or honey and libations to Selene after dark, because--in the cycle--this is the only night of the Noumenia and I feel Selene, the personification of the moon, is best worshipped at night, especially because we celebrate the first sliver of the new moon.
The next day (day 3, Noumenia day), in the morning, I offer the same type of sacrifice to Apollon Noumenios (Orphic Hymn 33, (parts of) Homeric Hymn 3, or Homeric Hymn 21), Hestia (Orphic Hymn 83, Homeric Hymn 24, or Homeric Hymn 29) and Hermes (Orphic Hymn 27, (parts of) Homeric Hymn 4, or Homeric Hymn 18). I also refill my kathiskos and offer a hymn (I tend to choose Orphic Hymn 14) to Zeus Kthesios, as well as incense. The goal of the Noumenia is to start fresh, and to honor the household deities. It is a day of family, family meals, and the celebration of the new month. Part of that celebration can be to prepare for the new month by planning out important events--religious or secular--and writing them down, preferably with the whole family present.
Either that night after sunset, or the day after, day four (Agathós Daímōn day), I offer incense, libations of unmixed wine and a hymn (I am partial to Orphic Hymn 72) to the Agathós Daímōn, the serpent household spirit, who brings good fortune, honor and wealth to the oikos, and ask it to watch over my family, keep honor in our family line and to let our family name be forever remembered through their deeds, and mine. I may also read out the list of events and goals for the new month to the spirit, so they may help me with it. After that, I'm ready for a new month.
This is how I perform these very important festivals. Others do it differently, I'm sure. A modern invention is to give either food or money to a charity, or a food bank on the Deipnon. This practice is based on a quote from Aristophanes' comic play, 'Plutus'. In a debate between Poverty and the character Chremylus, Chremylus says:
"Ask Hekate whether it is better to be rich or starving; she will tell you that the rich send her a meal every month and that the poor make it disappear before it is even served."
It's not the most... clear of statements. Some take it to mean that Hekate is fine with the poor eating Her offering, others assume those who took Her Supper were hungry enough to brave even the dread Goddess Hekate and Her spirit entourage. I'm partial to the latter, so I do not donate food or money to charity on the Deipnon. There are a lot of other days to do that on which will not potentially piss off Hekate.
All in all, the Deipnon is probably my favorite Hellenistic holiday. I love the sense of closure it brings, and the way I get things done I would otherwise avoid indefinitely. I can be very good at putting my head in the sand some days. My respect for Hekate most certainly blows that out of the window when the Deipnon comes around. How do you celebrate the ending of the old month and the transition into the new one?