Help Getting the % Change Between Two Dates, but filtering based on name?

Hi,

This is my table, it has:

- date index - that dynamically changes to show the latest date as 0.

- The date

- A name

- % Complete that week.

What I am trying to make is a column/measuer that tells me the weekly change based on the Name, between the previous date index (current row index + 1) and the current date (index 0) - as highlighted in red.

I'm guessing we also have to handle error cases for the "last" one, where there is no index +1 too?

I think I need to create a measure in three parts, one for the current % complete, one for the previous % complete (but somehow fitler based on the name of the current row and the index beign the current row's index +1, then the calcualting to subtract the two)

Any hints or thoughts?