How to reproduce the Time Lag report from Multi-Channel Funnels using Google Analytics 360 data in BigQuery?

I'm trying to reproduce the Time Lag report from Multi-Channel Funnels you see in the UI of Google Analytics, using the data of Google Analytics 360 (Universal Analytics standard) in BigQuery.

Any idea how to do that? The Time Lag report contains this:

The time lag report shows how long it took for a website visitor to convert from the initial visit to a website. You can view it for all channels or AdWords only in the case below. This shows that conversions happened fairly quickly for the majority of visitors, however there were seven that took up to a month from the initial visit before the conversion took place.