Website owners and companies usually mention the copyright period at the bottom of the website’s About Us page or homepage. We can use this information to predict the launch date of a website, but it also has many drawbacks.
The website owner may choose not to display this information on the website. The website may have been sold to a new company, and the copyright date represents the ownership date of the new company rather than the first company that launched it.
Also, even if the copyright date is given and is accurate, it only indicates the year of launch, not the exact day or month.