>> What is the average time it takes to run guiding calibration?
That will depend on the calibration pulse width that you are using, together with the image scale of your guide scope/camera. And the exposure time that you are using.
PHD2 recommends between 8 and 15 steps, for each direction. If you are exposing for 3 seconds, then a total of 30 steps (15 in each direction) will therefore typically take about a minute and a half.
Additionally, depending on the quality of your mount, it might take extra time to clear the backlash, too.
If you see the calibration process take much more than 15 steps in each direction, increase the calibration pulse width accordingly. Ditto, if it takes fewer than 8 steps -- then, reduce the calibration pulse width (in milliseconds) in the Guide setup window. E.g., if you see it take 35 steps and do not have the patience to wait, just increase the pulse width by a factor of 2.5 or so.
All info are in the PHD2 manuals. The guiding in ASIAIR is just a dumbed down version of PHD2.
Chen