Its really hard to tell how long it will take as strain is the biggest factor in this outcome..My only suggestion as to how long from pre-flower to smoke is, be patient. It can take a while with some strains..Youll know when its done by simply lookin at the "hairs". When you see some of them start to dry up and change color, harvest and cure that baby...

As for when to harvest it..Well day or night has never made a difference for me. But for security reasons ya may wanna harvest at night. If security isnt a problem, then simply harvest when you think its time, day or night..

PS- about your pre-flower then flower and then bud question. Well, its partially correct. A bud is a pre-flower in botony terms, but the cycle goes pre-flower-flower-mature flower...The "bud" that you smoke is nothin more than a mature flower..