I took the index of the words, converted the number to binary, added a few zeros, calculated the sha256 digest, took the initial part of the hexadecimal to transform it to binary, included 3 zeros to your 8 digits with the binary and received 00000010011 which translates to 19 in https://greatbookmarking.com/story19059264/facts-about-bip39-seed-phrase-github-revealed