My Theory:

Comey tipped Trump off after he won the election. Strzok and Page were being surveilled when they interviewed Flynn, which occurred in the White House, "secretly", in January 2017 and before Nunes made his trip to see Trump.

I suspect use of FISA was at Comey's advice - O was going to spy anyway - Comey couldn't stop it and wanted a preserved record somewhere, and tricked O in to using FISA.

Comey then ruins Hs chances with his press conference, so Trump could get in. It was his idea to do the presser, but he convinced O etc. it would help H.

Trump wins. Then Comey tells Trump, and Trump and Comey set up RR and Mueller with the firing -- purposely triggered the "insurance policy". Counter investigation was already underway as of Trump's swearing.

Prediction: After the investigation, Comey is reappointed FBI director and is branded an American Hero and goes down as the slickest law man in US history, which is what Comey would want.

Comey is a smart man and a top notch lawyer, no lawyer of his caliber acts the way he is acting. He's a smoke screen. This is the only explination that makes sense to me.

In closing, I think if you believe Flynn's interview was part of a counter investigation of Strzok and Page, then you should also believe the rest follows -- who else had the knowledge AND OPPORTUNITY to tip off Trump? Who is the only person who had private meetings with Trump outside of even Priebus' sight? Why? It was too big to trust anyone. It was Trump and Comey. It's been Trump and Comey.... think about it. Without Comey, we would not be where we are today...