Don't Load Data Until All 3 Sources Are Ready

Do you mean which LOB is the first to have the data? No. It varies.

I'm wondering if grouping by DateKey (eg. 2022-09-30) and then distinct count LOB would work, but I can't figure the logic out. I tried creating a Calculated table in Desktop with JUST the Date key from my data table, like so:

But it's not working. 

This is the result I was expecting to get:

My thought process is that I can use the "Count of LOB" column as a filter for the entire report, to only show data when it equals 3.