come up with a complete outline of a VERY short and narratively VERY simple story, then write it *all the way through*. like as absolutely basic of an idea and a plot as you can, even if it seems ridiculous, and then follow through. I’m talking like 3 events happen in your whole story! you’ll get a sense of how long it takes to write, how to blend scenes together, how to balance dialogue, etc.
Honestly, get all of your thoughts down as soon as they come to your brain! No matter where you are, if you think of a thought, go to the notes app and write it in a bullet point before you forget it. You can organize it later, just get that much written. Some of my bullet points are quotes I’ll have a character say or a small interaction written like “A gets coffee and bagels for B and brings it to work” or something idk. Just get your thoughts written
After that, you can start organizing and outlining. If you know the chart with intro, build, defining moment, climax, etc., you can grow your story from there and put in those small interactions that you had previously written down. Rough drafts are meant to be rough. The important part is that it’s there