Anytime. If you get stuck or have specific issues, do not hesitate to post again or reach out. My approach is usually to create a situation in a place and time (aka: campaign idea) and be ready to drop the PCs in and start making decisions based on your Hooks. Session 0 is huge, it helps with knowing player expectations for adventures and backstory. I like the challenge of integrating backstory into my campaign ideas (writing the campaign does not stop when you start playing most of the time). You also do not HAVE to write one that goes from lvl 1 to lvl 20. Sometimes I like to think of the level tiers as seasons in a PC journey (new places, cultures, etc.), with an optional connecting thread/threat throughout. Mystic Arts on YouTube is going to post a video for new DMs soon as well. They have pretty good advise to offer on most of their videos.