What gotspings mean is, set up your AP as you want (Wifi and SSID names etc) and then everything works you
add the switch on off function for Wifi i/f.
In system/Scheduler you can run scripts at certain time of the day.
Just put in the command you would enter into a terminal like below into the body of the schedule tab:
/interface wireless set MY_WIFI_IF disabled=yes
to disable it
/interface wireless set MY_WIFI_IF disabled=no
to enable it
Assign time of the day to run them as you want. With this the Wifi network will not work outside your hours.
For more control/granularity, use the "wireless"/ "Access List".
In the Wifi interface tab uncheck default authenticate, now you will need "access list entry" that someone can connect
to your network.
If you want to block everybody, just create one, leave all fields empty (you can also select which Wifi i/f you want) and assign
at the bottom of the tab under "TIME" the day and individual times of the day to allow access.