Now that this week is over, another few insights from myself in addition to the other answers.
I've not played much before and never DM'd. But I have watched a few hundred hours of D&D streams (High Rollers, Heroes & Halfwits), as well as Matt Colville's Youtube Playlist "Running the Game".
I'm not recommending any new DM with only two months or so left before playing to start this way, but since I had that knowledge beforehand, I already knew the rules and how the game works. If nobody in your group has ever played, including you, then it's probably very helpful to listen to some podcast of experienced players, just to get a feel for it.
First of all, realize that you cannot really fuck this up. As long as you're somewhat prepared, your players will be understanding if you need to look something up.
Also, realize that unpredicted things will happen and that the players share part of the storytelling. I expected there to be way more unexpected player behaviour though.
Get the stat blocks together
I was reading through the campaign book and whenever a creature appeared, I pasted its stat block from the monster manual onto some A4 sheet together with all the other stat blocks for the same location. (I could share my preparation for SKT, but this is useful in general: I almost never had to look up things in the Monster Manual.
Bring a Laptop
I bought the hardcover book for easy reading, but I also brought a laptop with me, with a PDF version on it. It makes looking things up easy if you can just ctrl+F your search term. Also, the PDF allowed me to continue reading while commuting by train.
OneNote proved itself useful as a note-taking tool, since it allows you to search even the text in pasted images.
WiFi was valuable, but not essential if you already have open what you need. In my case, mostly donjon and roll20 website pages for the weapons overview and some rules I knew I would have to look up again.
Create Player Characters in advance
At first I didn't plan to do this, but my players suggested to do that, and it's an amazing idea:
- You have time to incorporate them into the world
You can tell them some knowledge or secrets about the setting that their characters would know, but that are not essential, and that immerse them more.
Monk from Waterdeep
Your hometown used to be protected by the "Force Gray", but only when the government saw no better solution. Since they were known for collateral damages, people usually took the appearance of the frost giant Harshnag, their most recognizable member, as an indicator that the area was about to become a warzone.
Waterdeep is ruled by the Masked Lords, whom nobody else knows the identity of. Their public face is the Open Lord, currently a Lady called [...]
You get the gist. I wrote such a text with 3-4 things for every player, Mixing random trivia with reasons for them to join up or to be heading towards the place where the campaign starts, and with things that might later come up and would be more impressive if they already knew about it.
- It can take the players way longer to create a character than anticipated. It took my players two days of sitting together, instead of the anticipated 3-4 hours (including explaining the game).
- It gives them time to think about how their character is supposed to be. And that makes the game more than just playing strategically. This is something they mentioned when I asked afterwards what they enjoyed most.
Have a session zero
Know in advance what to discuss there. Most importantly for people you already know well seems to be to set their expectations for the game.
I told them for example that they must create a character that wants to adventure and to teamwork, and also that it is very possible that a character dies and that there can be things that are stronger than them.
"If you die because I misbalanced something, I'll somehow try to safe you. If you die because you're stupid, that's not my problem."
Set everything up as a test run
Does your GM screen stand on its own? Do you have enough space for your dice, your book, your laptop and a paper for taking notes?
Think about Maps
If you're in the same situation as I was, you won't have a printer available. Do you need to preprint some maps? Which places are suitable for theater-of-the-mind play (which my players preferred!)?
I have printed a bunch of generic maps from the internet, but not used a single one.
As we're already talking about the missing printer: Bring spare character sheets in case some get theirs dirty.
Make sure the players are prepared
The first fight, the party was almost wiped (none actually died) because the druid procrastinated thinking about their spells and thus they didn't have healing ready. (Sure, that wasn't the only reason. But it bothered me. Next time, I'll check that in advance.)
Have a few generic encounters ready
I prepared a few puzzles and wilderness encounters that I can throw in anytime if the players get so far off-track that I have nothing prepared. Haven't used those yet, but it provides peace of mind.
There's a nice guide and a similar guide on the dmsguild which helped me immensely: Firstly I read those to get an overview, secondly I started reading the campaign book page by page.
We haven't finished chapter one in this week that we were playing, so I never had to take some time to prepare more than what I already had. Which is everything up to the start of chapter four - that is definitely overkill. But if you have the time, reading as much as you can of the campaign allows you to improvise, figure out motives for the NPCs and have stuff ready in case the players go somewhere else.
SKT's set-up is great since every location on the map has a short description. I showed my players a spoiler-free version of the map in the book (which I found on reddit) which increased the sense of "This is open-world." by much!
If you're in the same situation as I and have a week of holiday set aside to play with friends, here's how our time in that week was used:
We arrived at about 17:00 and had to go buy some food. Did not play much then.
We slept in and played from ~12:00 to ~00:00. Some days we started earlier or stayed up longer.
Keep in mind that it takes time to cook, eat, and maybe go out for a drink in the evening or go shopping again when food/snacks go out.
We had to clean the rented house and hop on the train before midday, so we didn't play then.
Playing in the train was an idea that came up, but would have been very difficult unless I as the DM would have improv'd everything - not enough space for all my stuff.
In between, one friend was occupied with other stuff for a day. So in the end, we only actually played on 5 days, and not much on one of them.