by Ritesh

Using cron to shutdown your pi at defined time
Using cron job
sudo crontab -e
[add a root user crontab if not available]
0 15 /sbin/shutdown -h now
Time set to shutdown at 3.pm everyday !
or
0 15 /sbin/halt
If it is one time simple shutdown -h with time should work
sudo shutdown -h 15:30