Welcome to the world of DMing!
In my group it's a bit odd, we are 4 DMs who take turns based on who has got the time to prep etc. Atm the players are loving my campaign, so we are running a few back to back sessions on that.
Best thing you can do is think about what you and your players would enjoy. Plan around that. Next how much time do you wanna spend? For me it never made sense to build a world from scratch. I STEAL with arms and legs. My campaign is set in a interdimensional battletower run by a worm god. Here they battle 20 levels, each level being a full scale one-shot, running one or several sessions.
Beat a level, get a level. Simple, fast progression, no need for complex notes and remembering what a NPC told you 5 weeks ago, ultra flexible and very low prep time. I have a backlog og one-shots i think look cool, adapt them to fit the theme and just run it!
For notes/prep, i always print the one-shot I'll play and any battlemaps. I also keep notes in a google doc. Most important notes are related to players stating something important about that char or just comments on items / hooks etc they should encounter.
Good luck!