[2] T. K. S. Sastry and R. Kochhar suppose that the Vedanga Jyotisha was written in the period that it describes, and therefore propose an early date, between 1370 and 1150 BCE.
[7] This may be due to the incorporation of late Harappan astronomical knowledge into the Vedic fold,[7] an idea also proposed by Subbarayappa.
[11] Michael Witzel notes: [O]nly if one is convinced that Lagadha intended the solstice to be exactly at alpha Delphini of Dhanishta, one can date his observations back to the late second millennium.
These conditions were true when the calendar was first implemented, however in the following centuries corrections would have to be made in order for each yuga to maintain them.
The months of the year are called Māgha, Phālguna, Caitra, Vaiśākha, Jyaiṣṭha, Āṣāḍha, (Śrāvaṇa Adhika, if needed), Śrāvaṇa, Bhādrapadā, Āśvina, Kārtika, Mārgaśīrṣa, Pauṣa, (Pauṣa or Māgha Adhika, if needed).
The calendar follows the amānta system in which months end with amāvasyā (new moon) and being on śukla pratipada.