I've searched for this question for a VERY long time with no results.
So here is the answer, for me it took about 2 Hours.
If you want internet specs and/or computer specs for what I used let me know.
Also, if you haven't started the download.
Mountain Lion is $10 cheaper than Lion was, with over 200 new features.
Including a Siri-Like text to speech system named "Dictation"
It learns and adapts to your voice/accent the more you use it.
UPDATE: I just got it installed which took about 40 Minutes or a little less, minus the reboot time.
GET MORE FREQUENT UPDATES BY LIKING ON FACEBOOK
UPDATE: I just got it installed which took about 40 Minutes or a little less, minus the reboot time.
GET MORE FREQUENT UPDATES BY LIKING ON FACEBOOK