I took the index from the words, transformed the quantity to binary, included three zeros, calculated the sha256 digest, took the 1st A part of the hexadecimal to transform it to binary, added three zeros to your eight digits of your binary and received 00000010011 which translates to 19 in https://bookmarktiger.com/story18948890/5-simple-techniques-for-bip39-word-list-pdf