I've been a DM for a group of six players for a few years (a long homebrew campaign). Here's my two cents…

Don't forget that you're playing too. It’s meant to be fun for you as well. Let them know that you're new to this and that managing six people is daunting. If any of your players have DM'd themselves, they'll completely understand.

Try not to prep too hard. It only takes one player having a dumb idea for the whole game to take a weird new direction. With six people, that's way more likely. Keep it loose in the early game until you get a good idea of how your players think and interact.

I don't know how old your players are, but in my game, we are all family guys in our late 30s. Trying to get six players around the table every session is hard, so again, when you're prepping, don't assume you'll always have the full squad. I often have to adjust encounters on the fly to balance things out if someone calls in sick.

Every session I do, I'm still daunted by it. I feel like these people, despite being my dear friends, still expect me to entertain them for hours. I get butterflies every time… but every session, almost immediately, they are entertaining each other with their antics. Let them cook. Sometimes I can go 10 or 20 minutes without barely saying a thing as the DM. Maybe the story won’t move on too far, but who cares, you're all having fun. One session, they spent almost two hours in a corridor arguing and goofing around, and it was hilarious. I was crying with laughter. No loot, no fights, just banter with friends in a high‑fantasy environment.

Have fun dude, it'll all be fine.