Cummulative sum by one value till maximum

Hello,

I've created the following measure based on your measures:

The following line is generated by this measure:

This line starts at the first week of the year. Now I want to start this line chart at the same moment when the first production activity is registrated. This date value is " 'table - productregistration'[when] ".

Do you know what I should change in this Measure? Maybe it is relevant to know the following date table:

Thanks a lot for helping me out!