It probably was about 2 months of initial CAD and drawings, another 2ish months of manufacturing, a month of testing, a month of iteration, another month of manufacturing, more testing, reviews, qualifications. Add in some time for Davis working on other things + the part waiting for other projects to finish manufacturing or testing, and you get nine months.

For a cleansheet part from a engineer who never built one in his life during the early days of this approach to aerospace, 9 months seem reasonable to me.