Although there is a special light and sound show in maysore palace, but special event is organized on dashahara after navratri. it is world famous event organized in maysore. at this time whole palace is filled with lightning.
Mysuru palace is beautifully lit after 7pm on sundays only. But if you want to get inside of the palace you need to visit during 10AM to 5-5.30PM.
Hope you Will have a great trip to this cultural hub of Karnataka :)