Finding index of column sign change

[Anonymous]

I have a question regaring how to find the value of one column, when there is a sign change in the running sum of another. 

The columns i have look like this:

Where the running sum is a measure:

Running sum = 
VAR Runningfilter = FILTER(ALL('020_cashprofiles'[nummonth]),'020_cashprofiles'[nummonth] <= MAX('020_cashprofiles'[nummonth]))
Return CALCULATE(SUM('020_cashprofiles'[value]),Runningfilter)

How do i find the nummonth of the first positive running sum? I have multiple markets for which i need to find this and want to be able to filter it. My market structure looks like this:

Thanks a lot for any help.

[Greg_Deckler · Accepted solution]

@Anonymous - Perhaps

MINX(FILTER('Table',[running sum]>0),[nummonth])