If you need to postpone or cancel plans with someone then you can take a rain check. We use this expression when we want to politely decline an invitation or reschedule a plan, but also imply that we would be interested in accepting another one in the future.
If you have a project or task to do, and you have a very limited amount of time to finish it, then you can say that you're in a race against time.
When someone is on the ball, they pay close attention to the details of an activity or project. As a result, they are usually knowledgeable and quick to respond to changes.
Have you ever worked on a project that completely changed the way your business operates? If that project was the outstanding achievement that your company needed to grow, it was a game-changer.