Shutting down the radio
Do you plan to disable a given SSID during a specific time (stop broadcasting it) or do you plan to deny clients outside of a given time/day?
There are multiple ways in Enterprise to achieve this, e.g. by configuring a "Period Policy" as part of the "Access Role Profile" (see attached screenshot).
The second possibility would be to go through the API of OmniVista to turn on/off an SSID at a given time. This API is used in my GitHub project here: https://github.com/BennyE/stellar-ssid-onoff
Please note that this functionality is included in OmniVista v4.3R3 directly, which is our next release in Q1/2019.