I took the index on the words, transformed the variety to binary, included 3 zeros, calculated the sha256 digest, took the initial part of the hexadecimal to transform it to binary, added three zeros to your eight digits in the binary and received 00000010011 which translates to 19 in decimal. https://socialistener.com/story4282744/considerations-to-know-about-bip39-word-list-pdf