The older at command no longer works for simple scheduling of tasks so now we must use schtasks.
To configure a task to run one time, and reboot at 6PM October 13, 2022, I use the following command.
schtasks /create /tn "Reboot-Oct13" /tr "shutdown /r /f /t 0" /sc once /st 18:00:00 /sd 10/13/2022 /ru "System"