The Digambar and Śvetāmbara traditions did not begin as two separate religions. In Jain history, they are understood as two traditions that gradually emerged after the original Jain sangha.

A commonly accepted Jain historical understanding is:

• Division began around the 3rd century BCE, after the famine in North India and the migration led by Acharya Bhadrabahu.
• The Digambar tradition is associated with the path that preserved the ideal of complete non-possession and the ascetic practice of remaining without clothes.
• The Śvetāmbara tradition became distinct later as the community in western India developed its own monastic practices and scriptural preservation.

So, in simple terms:

• Root split: around 3rd century BCE
• Distinct traditions became established over the following centuries

If you want, I can also explain why Digambar and Śvetāmbara differ in simple Jain terms.