The question was on different angle: can single person compete with the whole IE team at MS to achieve anything viable. And that required the engine to be present to try by others.
Initial version was very basic HTML renderer named HTMLayout that time. Made site for it and published couple of articles about it. These allowed me to gather requirements and estimate interest/market for it.
After that modules of HTMLayout were assembled into Sciter, with additions of CSS and scripting.
As of 9 months...
I've participated in many projects, successful ones took 9 months from first PRD to alpha/beta stage. Longer projects, as a rule, were less successful. Team lost the steam, etc.
YMMV of course, but 9 months to create something, seems like is embedded into human nature. I cannot provide any formal proof, just a feeling supported by 30 years of experience in the business.