There were several stages of MVP. First usable version took a month and half to build and public launch with 2 IDEs supported was 2 and half months after starting to build.

May 3 2013 - Started development Flask website & Vim plugin (https://wakatime.com/blog/1-why-i-built-wakatime)

June 25 2013 - Finished Vim plugin and Website (https://github.com/wakatime/vim-wakatime/commit/4346a055e301...)

July 1 2013 - Started Sublime plugin (https://github.com/wakatime/sublime-wakatime/commit/b7fe36f8...)

July 15 2013 - Finished Sublime plugin and public launch (https://news.ycombinator.com/item?id=6046227)

Unfortunately I don't have WakaTime data until after finishing the Vim plugin, but everything after that I can see how long the actual coding took by dogfooding.