So... I got bored and worked this up.

The Equestrian year is 384 days long, and it has 13 months following a lunar cycle.

The months are:
01) Cold Moon (30 days)
02) Ice Moon (29 days)
03) Grass Moon (30 days)
04) Rain Moon (29 days)
05) Breeze Moon (30 days)
06) Rose Moon (29 days)
07) Gold Moon (30 days)
08) Fire Moon (29 days)
09) Harvest Moon (30 days)
10) Leaf Moon (29 days)
11) Frost Moon (30 days)
12) Snow Moon (29 days)
13) Silver Moon (30 days)

Each week has 7 days:
1) Sunsday
2) Moonsday
3) Firesday
4) Watersday
5) Woodsday
6) Metalsday
7) Starsday

Important dates that happen by this calendar:
*Hearts & Hooves Day = 14th Ice Moon
*Winter Wrap-Up = 29th Ice Moon
*First Day of Spring = 1st Grass Moon
*First Day of Summer = 7th Rose Moon
*Summer Sun Celebration = 16th Gold Moon
*First Day of Fall = 16th Harvest Moon
*Running of the Leaves = 15th Frost Moon
*First Day of Winter = 23rd Snow Moon
*Hearth's Warming Eve = 25th Silver Moon

Luna was saved/redeemed from Nightmare Moon on the 16th of Gold Moon in the year 1000. Events of the seasons 1-3 span one year. The Wonderverse Timeline therefore starts somewhere in the year 1001.

Also: I have unlocked the threads for the Concepts, Characters, and Places. Feel free to ask questions about said subjects in their respective threads. You may ask questions here about the calendar, including when we've slated some of the birthdays.