You get to choose 1 no from the idol Board in 12 hours. That makes it 2 choices in a day.
Note : There should be a gap of 12 hours in between both the choices or else it won't be accepted. If you stilrepeat the mistake 2 times, I will notify you. If you keep repeating then I will text you saying "No Idol" even if it has an idol.
There's one more idol. Called the Super idol which will give you unimaginable power in this game. Details about it will be revealed later. It won't be retrieved from the IDOL BOARD.