Vydor speaks truth.
You are just finding out your working process. Don't over-analyze it now because writing anything is infinitely better than writing nothing. Just know that there will be a significant edit and rewrite phase no matter which process you use. Don't let that cast a shadow over getting your words on paper. It doesn't matter how many scenes/characters/clever turns of phrases you don't end up using. Nothing is wasted if it gets you to the finish line.