when the balloon goes up

When the situation becomes serious, critical, chaotic, or troublesome. Our analysts have been predicting a market crash for months now. If we don't get diversify our assets soon, we're going to be in serious trouble when the balloon goes up. My parents' relationship has been on the rocks for years. I just hope I'm out of the house when the balloon goes up.

when (or before) the balloon goes up

when (or before) the action or trouble starts. informal

The balloon alluded to is probably one released to mark the start of an event.

1959 Punch The international rules of war are apt to be waived when the balloon goes up.

when the balˈloon goes up

(informal) when the trouble or important event begins: I don’t want to be there when the balloon goes up.