Carakan was 16.5 months from first commit to shipping (and a month or so more to not being notably buggy), with a team of five for the vast majority of that time. The only code carried over verbatim from Futhark was the regexp engine (though that had machine-code generation added to it), and the parser was also pre-existing (though not shared with Futhark!).

For comparison: MS were the last to do a major rewrite of their layout engine, which started, AIUI, before IE7 shipped (Oct 2006) and shipped in IE8 (Mar 2009), and more-or-less reached feature parity with others with IE9 (Mar 2011). To be fair, they were working from a far more archaic codebase than anyone else, so probably had more work, but they also had a far larger team than anyone else working on this.