Have you heard about this book How to Write a Movie in 21 Days? It’s not a bad book. It’s not bad advice. Grab it here. If you write a screenplay, you should write it in 21 days.
But if you’re trying to write your first screenplay, you’re not going to write a good one in 21 days. But that’s okay.
The more important thing, when you’re a beginner, is to write your script fast. The faster you can write, the sooner you’ll get good at telling stories. You can do this even faster than 21 days by doing one little workaround.
Instead of writing out a whole script, write out your story idea in paragraphs in a two-page story treatment that you could read to someone in ten minutes—your whole story, beat by beat.
If you want to see what one of these looks like, click here. I’ll send you one that I wrote.
Next, read your treatment aloud to people and get their feedback. Keep reworking that two pager until you get a story that works. When you do, file it, and start another two-page treatment for a totally different idea.
As soon as you get a two-page treatment that not only works, but people are telling you is great, adapt that one into a screenplay. That would be a good first screenplay to write.
The number one problem almost scripts have is the story doesn't work. This little trick will give you a fighting chance to beat that problem.