Just stop using the word index and start using the word offset.
Problem solved.
The notion that the first brick in a run has an offset of 0 as does the first upright stud in a frame is something that's been basic to bricklayers and carpenters for a very long time.
Sometimes it's natural to refer to elements by their position, or offset, other times it's natural to talk about sequence numbers or indexes.
There are only two hard things in Computer Science: cache invalidation and naming things.
-- Phil Karlton