Should have been fired at 12:01pm, 1/20/2017.
correct
Yes and in fact I’d go further and say that In addition to saying that’s when he should have been fired Trump should recommend that all future incoming presidents, whether or not a party-changing event, immediately fire the FBI director in defiance of that non-binding ten-year term to avoid the accumulation in an office that can make someone so powerful that they can undermine the entire agenda of the incoming president - and thus of the voters.
First he needed to put someone in place to clean out Comey’s office.