BTW,
Here is a strong hint that the investigation was opened LONG before the time the FBI says it was.
https://www.youtube.com/watch?v=bui45pQcy6E
March 2, 2016 Carter Page meeting – during a meeting where they are discussing him testifying against the three Russians in the case that resulted from his informing between 2008-2013, Page advises he recently volunteered for the Trump campaign.
Remember that they got the *first* FISA warrant AFTER Page had already left the Trump Campaign.
The lawyer goes back after the meeting and asks whether he has a clearance, and inquires as to what kind of investigation to open on him.
I think the only thing that wasn’t known may have been that an FBI agent committed fraud on the president by pretending to be there for a President’s Daily Brief when he was actually spying on the president. The entire FBI needs to be sent to the crusher and landfill for that.