Have you decided your circuit design?
If you were to use an ESP8266 module with a 8x32 matrix it would be very easy to wire up.
The reason I mention using an ESP part is that they are very small and you could use the wifi for configuration (using a web browser on your tablet, phone, pc, etc...) as well as getting time from a time server so you also won't need a real time clock battery, buttons, or switches.
And you can could have it automatically do daylight/summertime time adjustments.
If you put a piece of paper or onion skin over matrix, you won't see it but can easily see the leds that are turned on.
--- bill