It's quite easy if you understand that the solution isn't intuitive and obvious as it should be. 

Attached is a photo example for scheduling the Wireless to be switched off from Monday to Friday between 19:30 hrs. to 07:30 hrs. on the following day.  After you set the schedule to 24:00 hrs. in the first setting, it will appear as 0:00 hrs. once it's saved.  The schedule must however be set to 24:00 hrs. to work.  In the second setting, it should be set from 0:00 hrs.

I got in touch with someone from TP-Link and they didn't even know how to do it.  I came up with the solution on my own as I was explaining my situation or rather venting my frustration to the representative at TP-Link.  Hope this helps.