I took the index on the words, transformed the range to binary, extra 3 zeros, calculated the sha256 digest, took the 1st Element of the hexadecimal to transform it to binary, extra a few zeros to your eight digits with the binary and obtained 00000010011 which translates to 19 in https://sites2000.com/story8441945/the-5-second-trick-for-ledger-seed-phrase-bip39