Kieran and I got sort of a slow start. Kieran had been working on the idea for at least a few months before I joined him in May 2008, and he was Entrepreneur in Residence at NEA at the time. We got funding in August of that year, hired our first engineers in early 2009, and the first betas of the product went out to customers in November of December of 2010. So development took about two years, which is about what Keiran and I predicted at the time--- writing a new file system from scratch takes time. But more like two and a half if you count time spent working on the idea and validating it.
Our initial funding round was $4.6 million from NEA (New Enterprise Associates) We raised another round lead by Lightspeed Venture Partners in July 2009, for $12 million. That got us through initial product development.
Series C was in June 2011, not long after our public launch of the product, for $18m: http://www.marketwired.com/press-release/tintri-closes-18-million-series-c-funding-1526907.htm There were three later rounds prior to IPO.