Cohort Based Attribution

Here's one simple tip that I wish was easier to actually do. 

Identify all the new leads that were generated in a given month and see what was their first touch attribution source. 

Then, each subsequent month, see where those leads are in your marketing and sales funnel. 

How many became an MQL in month two, how many became an SQL, and how many turned into a closed won or close lost customer?

How many turned into customers in month two, three, four and so on. 

Most importantly, see what was the last source and offer they converted on before becoming an MQL, SQL, or customer each month. 

This would be such a powerful set of data yet I can't find one software tool that does this out of the box.