How can I specify shutdown time with "sudo shutdown"?
From man shutdown:

-r      The system is rebooted at the specified time.


[...]

 time    Time is the time at which shutdown will bring the system down and may be the word now
         (indicating an immediate shutdown) or specify a future time in one of two formats:
         +number, or yymmddhhmm, where the year, month, and day may be defaulted to the current
         system values.  The first form brings the system down in number minutes and the second
         at the absolute time specified.


More to be found at “How to shutdown Linux at a specific datetime from terminal?” on Unix &amp; Linux Stack Exchange and The OS X-specific man page.