"The Calendar months" or "the labours of the months" used and spoken in most parts of Middle-earth:
The timelin of Middle-earth revolves around 1670 P.C. (Post Cataclysm, after the last great starstorm. An event where the ground broke and rose aloft and tempestical powers of destruction followed after many great stars fell).The selected dates are sacred days which are celebrated and worshipped by many across the lands in honor to the old gods.
January - Feasting (5th of the feast)
February - Sitting by the fire (21st of the open flame)
March - Pruning trees, or digging (14th of prune)
April - Planting, enjoying the country or picking flowers (3rd of planting)
May - Hawking, courtly love (12th of hawking)
June - Hay harvest (10th of the early harvest)
July - Wheat harvest (29th of crops)
August - Wheat threshing (17th of spirits)
September - Grape harvest (2nd of the grape harvest)
October - Ploughing or sowing (>15th of ploughing | 16th< of sowing)
November - Gathering acorns for pigs (6th of the gathering)
December - Killing pigs, baking, hunting (3rd of the hunt)
The high elves´s definition:
1. Morning Star
2. Sun's Dawn
3. First Seed
4. Rain's Hand
5. Second Seed
6. Mid Year
7. Sun's Height
8. Last Seed
9. Hearthfire
10. Frostfall
11. Sun's Dusk
12. Evening Star