Canon LBP7210Cdn Manual page 347

When eight or more hours has elapsed from the time the printer entered the sleep mode
until the time the sleep mode was canceled
Calibration or correction of a phenomenon of "Out-of-Register Colors" will be performed
according to the setting of [Quality Correction] when the sleep mode is canceled.
* Depending on your environment, calibration or correction of a phenomenon of "Out-of-Register
Colors" may be performed even if less than eight hours has elapsed.