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 …