It's difficult to pinpoint a single "first model" of DNA, as the understanding of its structure evolved over time. Here's a breakdown of key milestones:

* 1953: James Watson and Francis Crick published their groundbreaking paper proposing the double helix structure of DNA. This is often considered the first accurate and widely accepted model.

* Early 1950s: Other researchers, like Linus Pauling and Maurice Wilkins, were also working on models of DNA, but their proposals were ultimately incorrect.

So, while 1953 marks the publication of the definitive model, there were earlier attempts at understanding DNA's structure. It's important to recognize the contributions of all scientists involved in unraveling this crucial molecule.