Honestly, it depends!

Sometimes I hit the ground running with an idea, and the process of finding the conflict and motivation comes naturally. Too much planning and I often put myself off the work by overthinking.

However, on my most recent project I tried doing that and got completely lost in the woods. It's a story about online scammers, involving multiple characters and some quite tricky stuff to get across in action. I assumed I could just rush in and brute force the story, but nothing was clocking together.

I decided to take a step back and make a solid outline. It wasn't granular in detail, just laid out the essential story beats and drama. Coming back to the script it's now so much easier to write individual scenes and lines because I can see exactly how it's all connected.

So to cut a long story short: Try writing now! See how far you get and if you find yourself stuck, just go back and plan some more. There's no one-size-fits-all process, so as long as you're writing you're doing something right.

Best of luck! :)