Run these in an administrative or SYSTEM-level command prompt.
In Windows 8.1/2012R2/10/2016 and later, we set a scheduled task, we do have to specify the actual full date:
schtasks /create /tn "schtasks_REBOOT" /tr "C:\Windows\System32\shutdown.exe -f -r -t 0" /sc once /st 04:00 /sd 01/01/2016 /ru System
In 8/2012R1, we have to have a “/Y on the very end:
schtasks /create /tn "schtasks_REBOOT" /tr "C:\Windows\System32\shutdown.exe -f -r -t 0" /sc once /st 04:00 /sd 01/01/2016 /ru System /Y
Under 7/2008R2 and before, it was easier, we could schedule for 4:00 AM tomorrow:
AT 4:00 c:\windows\system32\shutdown.exe -f -r -t 0
and we could schedule for 4:00 AM next Monday:
AT 4:00 /next:Monday c:\windows\system32\shutdown.exe -f -r -t 0