In my experience, there's a perfect window for getting your ideas down on paper (or screen). Too soon and the idea is barely formed and once committed is very difficult to develop further. Too late and the excitement of a new story will be lost.
You need to mull an idea over and hit the keyboard at the exact right moment.
Easier said than done, I'm afraid. At least in my case.
So, how do you manage those story ideas for optimum effect? All ideas gratefully received.