Initialize random selection confirmation

Hi there!
I would like to implement a random “selection confirmation” (the chatbot asks if the selection was correct). I have created a variable and added the various sentences, separated by comma (did you select correct, go on with this,etc). Do I have to add a decision point where I compute the random selection in every dialog or can I add it once a the very beginning of the whole intervention?

Thanks and best,
Sandi