I took the index on the words, transformed the quantity to binary, included 3 zeros, calculated the sha256 digest, took the main part of the hexadecimal to convert it to binary, extra 3 zeros towards the 8 digits of the binary and got 00000010011 which translates to 19 in decimal. https://myeasybookmarks.com/story4664163/top-guidelines-of-bip39-word-list-pdf