In an electrophotographic (EP) device, methods and apparatus include determining a delay of one or more sensors (hsync) to accurately know when to start the process of scanning latent images. In one aspect, the sensor includes a leading and trailing edge defined along a direction of laser beam scan travel. Determining the delay includes learning a position of a laser beam on the sensor at a time when a controller connected to the sensor receives a signal from the sensor indicating the sensor is being sufficiently impinged upon by the laser beam. It also includes learning a latest possible position of the laser beam along the direction of laser scan travel where the laser beam can be turned on and still have the sensor assert a signal indicating it has been sufficiently impinged upon by the laser beam. Bi-directionally scanning EP devices are also disclosed, including controllers, photoconductors, sensors, etc.