Holding a lightning rod in my fingers... well sorta

I've held the scene in my head for over a week now. Revised it, considered how it should be written--in first person? No. In third person? I don't want to be in any one's head, really, but maybe the more I work with it the more it will lean in that direction.
But you may wonder why not in first person--as in from Sabrina's POV?

Because she isn't there at the onset of the beginning of this scene. I'm doing a little something different, where I'm switching POV completely--going from first person to third, depending upon whose eyes I'm showing the scene through.

You see, I began writing the fourth novel and realized I couldn't write this one without going into other character's heads. It was the only way to tell it. So, possibly my fifth novel will borrow this sort of POV switch. At least in the beginning. I don't know what will happen once I'm past the first chapter. But I love the control I have when I write. As the writer you can do anything, within reason, and your readers should, hopefully, accept it if you do it well. I remember reading a book by Sunny, called "Lucina, Darkly" and found that she had switched POV completely from third person to first, from one chapter to the next. I'd never seen this done before. It took me a few confusing moments to understand what happened. It was almost like someone had pulled the rug from beneath me. But once I got used to the idea, I was fine with it.

It was brilliant, I thought. I also thought, maybe someday I should try that. So... that's what I've done. I plan on an author's note to readers in the beginning, however so that I'm not throwing something at them that they aren't used to.

At any rate, since I wasn't able to hold that scene in my head any longer, and it wanted out of me (you know the feeling, I'm sure), I went to my temporary file where I tinker, and put it down. Before I knew it--4 pages of the scene emerged. Then, today I've worked into page 5. I've now got it into it's own file for Crescendo. So, it's official. Yes. I've begun the fifth book with a 3rd about to be sent to publisher at some point late winter, early spring.

Is it hard to hold a scene in your head, but you wait until you've nurtured it some? Or do you begin writing something as soon as you've thought of it?