Line/Indicator to show where the recovery date is on a line graph

[jabbajuice08]

How would I write a DAX measure for displaying the date that my measure BCWP/BCWS goes up to 90%? 

I have a 'calendar' table and a 'cost' table that are being used in the line graph I need to display this DAX measure. They are connected by 'calendar'[ID] = 'cost' [ FC INDEX] OR 'calendar'[ID] = 'cost' [ BL INDEX]. I have both relationships inactive so that I can pick whichever I need, depending on the circumstance of the measure I'm creating. 

My BCWP/BCWS measure is in my cost data (also the measure in my line graph) , and DATELABEL is in my calendar table (also the shared axis in my line graph). 

I need to create a line on the x-axis that displays the date of recovery....so when BCWP/BCWS hits the 90% mark.