God's Calendar

Days

A day is the length of the cycle of The Watcher's gaze. For half the time he gazes upon the world and tallies the sins of all he sees, judging evil things and smiting them. During this "daytime" the horrid things on the moon plot and scheme and the stars draw closer, so The Watcher turns his gaze around and plunges the world into darkness. The things on the moon retreat to their tunnels and crates and the stars cease their motion, while criminals and monsters and undead roam free to plague the world below. When all the moon-things have been driven away and the scoundrels of the world have had enough time, The Watcher turns around and the cycle begins anew. 

Weeks

In the world before the sun, time was kept by the roaming of the titans around the world. This was useful because each had it's own purpose, a visit from Wood grew plants while Ice killed them, Cloud brought the rains and Lightning the storms, and once a land had been visited by every titan at least once, another "week" was marked. Once the titans were contained and The Watcher vigilant in the sky, this denomination was kept to sort the days into neat groups of seven.

Months

The moon is full of things that glow and dim, that move and change, and as such the surface of the moon glows and dims with them. This once was unpredictable and chaotic but the Serpent Queen bound the moon to the world and as such bound the cycles of the moon above to the cycles of the world below, such that they would sync. When the gods calmed the elements so too did the moon calm with them by the Serpent Queen's chains, and now it cycles once per week, from full to half to none to half to full again, growing in power and influence and weakening again. Four weeks make a month, one full rise and fall of the moon.

Years

The year did not exist before the gods, it was specifically designed when they bound the elements to stability. They each claimed a month for themselves and left a tenth empty to remember their fallen brother The Judge, and then wove the seasons to make a time of planting and time of harvest, a time of life and a time of death.

Ages

The world is young, or at least the calendar of the gods is young. The years are split by an event known as "the calming", which marked the end of the great genocide and banishment of the peoples of the Beastlands, by the dwarves building fortresses in the Beastland Pass, thus stopping the wars and allowing civilization in the North to flourish. (For reference, my first campaign took place in the year 216 After-Calming, less than even the life of a single dwarf).

Seasons and Holidays

The year is split into four uneven seasons, Spring and Fall having two months each and Summer and Winter having three. Each month is claimed by a god, and each containing a holiday or holy period on or surrounding the 17th day of that month. Holidays are celebrated in all the god-worshipping lands in the North, though they may be more or less prominent based on the prevailing local gods, and are not paid any attention in the Beastlands of the south. They are as follows:

1. Month of the Cultivator - The beginning of spring, a time of planting and new life. It's holiday is a week-long Birthing Festival, where mothers do not die during childbirth, children always come out healthy, and animals are born strong and powerful. Nobles will often (unsuccessfully) attempt to time it such that their children are born during this festival, or engage in questionable rituals and magics to ensure such.
2. Month of the Mage - The end of spring, a time when all are restless and plans for the upcoming year are made. The 17th day of the month is Opposite Day, holy to the tricky and mischievous god. All who do the proper prayers and play truly impressive pranks will have their lives flipped, Fighters turning into Magic-Users and vice-versa, and Clerics into Thieves and vice-versa (alignments would be flipped as well, but I do not use alignment in my games since The Judge is dead).
3. Month of the Watcher - The beginning of summer, when The Watcher grows brighter and his gaze even more ever-present. The 17th day of the month is the Festival of Calling, when any town which collectively does the proper prayers and makes the proper sacrifices (usually 5000gp worth of rare incense and burnt offerings and such) gets an angel sent by The Watcher to aid them. Either by answering questions about the vastness of all under the sun, or holy smiting with all the wrath of the sun.
4. Month of The Champion - The middle of summer and the hottest time of the year. While most would want to spend this time lazing about, the strong and righteous take part in Departure Day. Any who depart on a holy quest that is Champion-approved will have their quest blessed (lowered chance of unwelcome random encounters and increased reaction rolls), at least until the end of the year.
5. Month of The Warrior - The last month of Summer and a common times for wars and raids at the end of campaign season. The 17th day of the month is Fisticuff Fest where the bloodthirsty goddess demands conflict. All attack and damage rolls are made at +2 and brawling is not punished in most settlements as to not incur the wrath of The Warrior (as long as it doesn't get too out of hand, like random murder sprees).
6. Month of The Inventor - The beginning of Fall, and harvest season. The 17th day of the month is called Math Night by the whimsical goddess, as all who give prayers do not need to sleep and she wishes they would stay up doing calculations (though most just relax or work twice as hard).
7. Month of The Architect - The end of Fall, a time when all are rich with food and must cooperate to prepare for the coming Winter. The 17th day of the month is Crowning Day, when The Architect solves political conflicts by smiting unworthy kings wearing crowns and blessing the worthy. For some reason, it is common tradition for rulers to set their crowns down for the duration of the holiday.
8. Month of The Seer - The beginning of Winter, a time of anticipation and determination. Those wishing to take the edge off participate in the High Festival, a week-long period where those who smoke, lick toads, or otherwise get high are blessed/cursed with spontaneous prophecies and premonitions by the wise goddess.
9. Month of The Keeper - The middle of Winter and coldest month of the year, gloomy with death from the cold and disease, The Keeper's angels working double-time to keep up with all the souls. The 17th day of the month is Grave Day, when angels of The Keeper are ever-present, resurrections impossible, and undead dormant pretending to be corpses. It is a time when necromancers are confronted without fear and tombs secured and reset to ensure the undead within do not escape.
10. Month of Remembrance - The end of winter, and a time to remember the dead god The Judge. There is no holiday for there is no god, but some celebrate their survival of Winter nonetheless.