I took the index on the words, converted the range to binary, added three zeros, calculated the sha256 digest, took the very first Portion of the hexadecimal to transform it to binary, extra three zeros for the 8 digits of your binary and got 00000010011 which interprets to 19 in https://bookmarkextent.com/story20533608/5-simple-techniques-for-bip39-word-list-pdf