That depends what you count as a starting point – there’s no definitive answer. We’re a collective rather than a company, so we don’t have a fixed incorporation date.
Ultimately, Skywind is effectively the same age as Skyrim, because it started as a port of the original The Elder Scrolls Renewal project ‘Morroblivion’. (In fact, some aspects of Skywind, such as the voice acting project, are older than Skyrim itself!) Modders from Morroblivion started tinkering just a day or two after Skyrim was released, in late 2011. With the release of the Creation Kit on 7th February 2012, porting of Morroblivion began in earnest, and six months later, Skywind had a name and logo. So if you want to bake us a cake, the 2nd August is as good a date as any!
Since then, the nature of the project morphed into a game that will recreate every asset, from texture to mesh to sound. This was a gradual change, not a pivotal decision on a specific date, leading to the total remake project that Skywind is today.