Here we go!
Let's start! · It's happening now! · Here it comes (often with a sigh for something predictable/annoying)
What's the situation?
This is a super versatile phrase you can use when something is about to start, especially when there's a little excitement or anticipation! 🎉 Or, sometimes, when you're sighing because a familiar (and maybe slightly annoying) situation is happening again. Like when your friend starts telling that same old story... again! 🙄