Is MIN/Filter the right approach? Help - Sample data in link

Hi Power BI Community - 

Our marketing leaders have asked if we can build out some custom attribution models for marketing campaigns in PowerBI.  Based on what I know of the data, this can be done.  I think I have a good idea of how to approach this but I am hitting a snag using MIN/FILTER DAX to get what I need.  I have some sample data and the desired results and I am hoping someone in the community can assist or point me in the right direction.  

Business Problem:  Leads respond to marketing campaigns at various points in their buying cycle.  We would like to attribute a percentage of the won booking dollar value to the marketing campaign a lead responded before various milestones in the buyers journey.  Each of these milestones have a date/time recorded in our database

The milestones are:  

1. Lead Created in System 
2. Opportunity Created in our System
3. Opportunity Closed Won in our System

We would like to look at our opportunity table and a campaign response table and pull the date that is equal to or less than the date of the milestone and attribute a percent of the won deal to that touch point.  

Our model to attribute a percent of won opportunity dollar value to the campaign:

1. Lead Created -- Attribute 50%
2. Opportunity Created -- Attribute 25%
3. Opportunity WOn -- Attribute 25%

HERE IS A PBIX FILE with sample data

Here is what would be a desired outcome: