I took the index of the words, transformed the selection to binary, added 3 zeros, calculated the sha256 digest, took the first part of the hexadecimal to convert it to binary, extra 3 zeros to your 8 digits on the binary and bought 00000010011 which translates to 19 in decimal. https://bookmarkfame.com/story18889601/getting-my-bip39-words-to-numbers-to-work