In which event I put it On Init, On Timer or on Tick because I still understand if it goes on tick it runs on the first tick of the new candle but not the opening of the candle.

Greetings. I have a doubt, I want to create an EA that opens the operations to the opening or closing of each candle but not on each tick. I appreciate if someone can guide me on this to know what block to use. Thanks in advance.