Choral Music Formating

I've been trying for a long time to find a real answer to this question and I can't find one. In choral music when the piano introduction is playing and nobody is singing the staves of S.A.T.B are not there, they are invisible and don't exist. How do I do this? The first four measures of the song are piano with no singing and then vocals come in. How do I not have the vocals come in until measure five. This is seen in every form of choral music that is written like this. Also cutaway and hide staff are either not what I need or I am doing it incorrectly. I've included an image of what I'm talking about.