Honestly, I don't trust built in our cheap outlet timers. They fail constantly. I got a wifi enabled one from Walmart called TouchSmart. It needs to connect to a router and will only fail if you unplug your router (if you lose internet, it works fine!). Otherwise, you just have to download an app to set your timer to whatever hours you want.
I realize this probably didn't answer your question, but like I said, I don't trust cheap or built in timers.