I took the index with the words, transformed the range to binary, included 3 zeros, calculated the sha256 digest, took the first Section of the hexadecimal to convert it to binary, additional a few zeros on the eight digits of your binary and received 00000010011 which interprets to 19 in https://bookmarkdistrict.com/story18581133/considerations-to-know-about-bip39-word-list-pdf