If you come to use a computer that is not turned on, the below will help you reduce the amount of waiting time.

When a computer turns on it presents the logon screen before it is really ready to be used.  For about 30 seconds to a minute after the logon screen is displayed (depending on the age and speed of the computer), the computer is still doing things in the background.  If you try to logon whilst these background task are being completed, it dramatically slows down the logon process.

You’ll find that it much quicker if you wait for one minute after the logon screen appears before you try to logon, that it takes if you logon straight away when presented with the logon screen.  The older the computer, the greater difference in these times it takes.