We have almost no way of properly/accurately tracking a rouge black hole (they move near the speed of light and consume everything in their path). Just fruit for thought that I thought I should provide you with.
A Black Hole with sufficient mass to consume our planet would cause strong and noticeable gravitation disruptions that we would be able to detect even if it's 3 years out.
As far as I know, know such anomalies have been detected.
