Dwarven Time and Calendar

Dwarves very stubbornly stick to their own calendar, as a point of pride and tradition. Their calendar--the 351 days--follows an organization shared now (ironically) by many Elven civilizations and some other sentients.

The calendar simply marks the two solstices and two equinoxes as the Centers of Days, in the middle of the appropriate seasons. The days then are divided into eigths of the year. For example, the first month is called Winter One ("Hadd'zir"), and it consists of 44 days, as does Winter Two (("Hadd'zemm") after the Winter Solstice). Spring One ("Seff'zir") then begins at 88 days, with the Equinox bringing Spring Two ("Seff'zemm"), and so one.

The Calendar Days are thus named (although in Dwarven): Winter One Twelve, or Spring Two Thirty-Seven, etc.
Importantly, at the end of Fall Two is a "skip-day," in honor of the Solstice but also a practical leap-day to complete the Solar year in sync. Fall Two has 43 days rather than 44, to preserve the 351-day year.

THE FOUR BROHD ZELLOR MOONS (MYTHIC ONLY)

The moons sometimes carry festivals and observations with them in various regions of Brohd Zellor.

• Zizz and Zazz: Two small moons that orbit around each other (One slightly green, the other white), no phases; always there
• Skazz: Large silvery moon, casts magical-mystical silvery light, wanders ponderously across the sky, has 60 day phases
• Kozz: the “Day Moon” or “The Hammer”, because of a vague hammer-shaped blotch… Very large moon, relatively often eclipsing the sun to some degree
  

Determining the Current Dwarven Year

As the first day of the Dwarven Year coincides with the first of the Aligorian (world standard, for lack of a better system), the calendar year for Dwarves can be determined by simple math. The first year of the Dwarven calendar is the mythical beginning of the First Age of the Dwarven people. This First Age--an emergence of new Dwarven culture, more modern and "New" (so they say)--was a rapid expansion of Dwarven culture, including exponential improvement in industry, mining, and stonework.
The First Age is looked upon as an ideal time, a kind of utopia, a time before Eskil's Bane and the Corruption of Kings. Stories of the First Age are told in a wistful and dreamy tone. One dare not criticize such tales, or speak ill of the FIrst Age, for its memory (accurate or inacurrate) is sacred to Dwarven Societies.
In any case, the Dwarven year zero can be determined by taking the Aligorian year (also used on the timeline of the Dwarves) and subtracting 2752 years.

Solstice and Equinox Holidays

The Solstice Holdays are among the most important. For the Summer Solstice, sDwarves come above ground and trek to top of the highest mountain to watch the sunset, while sharing food and drink and honoring The One True Eye, Master of the Sun and Season, both his depth in the mountain an his emergence above.  These celebrations harken back much further than even the Scholar Society can delve.  They conclude that it must have emerged into the world with the first dwarves themselves.  Some say the traditions were borrowed from a Friend of the Dwarves in time beyond reckoning.
Equinoxes are lesser holidays, usually observed underground at shrines tunneled from rock, or within shrines and temples in the city. Equinoxes are less holy, but moore subject to the swilling of ale, contests of strength, and general revelry and celebration.
Of course, different ethnicities of dwarf have different approaches in some ways, but mostly the emphases are unified among them.