Disable network during specific hours?

I'm really, really new to OpenWRT and a novice at networking in general. Following a tutorial online, I had entered the following into my Scheduled Tasks:

30 0 * * * ifconfig wlan0 down
0 6 * * * ifconfig wlan0 up

This appears to do nothing. :) What is the correct way to kill my wifi from 12:30 AM to 6:00 AM?