The first state to host a Democratic primary is considered unusually influential due to setting the initial hype for the rest of the primary. In 2020, the first primary was the Iowa caucus which was somewhat bungled in a way amplified by how close Buttigieg and Sanders were, and lead to the resignation Iowa Democratic Party Chairman Troy Price; in 2024, the first official primary was in South Carolina.
Currently, several states are vying for the position of first:
If multiple states have the first primary on the same day, this will resolve as % weighted by the number of delegates that they have in the DNC for those states.
If a primary is unofficial and does not send delegates to the DNC, as New Hampshire dems attempted in 2024, then this does not cause the question to resolve.