I’m guessing I’m not the first to report this but according to SiRen, Si proposed on 2/24/18
Josiah Proposed to Lauren on February 24, 2018, Apparently.
Yesterday (February 24, 2020), Josiah posted on his (and Lauren’s) Instagram: “Can’t believe it’s been two years ago today that I asked Lauren to marry me.” Grammar issues aside, this obviously means that he proposed on February 24, 2018.
Prior to this, we didn’t know the exact date that Si + Lauren got engaged, but knew it was within days of Lauren’s youngest brother’s (Duke’s) birth. (He was born on February 21, 2018.) Duggar Data was using February 23, 2018 as an Estimated Proposal Date.
Based on this data, we now know the exact length of Si + Lauren’s engagement. (It was 127 Days, and still a Duggar record. February 24 to June 30, 2018.) We still don’t know their exact courtship length, though, since their exact courtposal date remains unknown. (Duggar Data is pretty confident that it was January 6, 2018, though.)