You volunteered back in July, when Week 1 was theoretical and generous. It is not theoretical anymore.
Hosting a kickoff party is mostly a sequencing problem. Very little about it is difficult, but certain things have to happen before other things, and the ones that go wrong are always the ones that got left until Sunday morning. So here it is as a timeline rather than a shopping list.
Two weeks out: order, because boxes don't teleport
Party supplies are the one category with no late workaround. You can buy chips on Sunday morning. You cannot buy a team table cover on Sunday morning unless you happen to live inside your team's home market, and even then it's a coin flip.
Order the licensed pieces early: plates, napkins, cups, and the table cover in your team. The Rams, Patriots, Broncos, Colts, Jaguars, Jets, Dolphins, Seahawks, Raiders, and Lions lines are all deep at the moment, but Week 1 is when the entire country decides to buy at the same time. Get it done while the picking is good over in NFL party supplies.
The week of: count seats, not guests
The useful question isn't "do I have twelve chairs." It's where do twelve people physically sit, for three hours, holding a plate and a drink, with a view of the screen.
Most living rooms top out around eight comfortable spots. Past that, people stand, lean, or end up on the floor. Standing guests need a surface within arm's reach for a cup or they will find one, and it will be your windowsill. One folding table along a wall solves more problems than any amount of extra seating does.
Saturday: everything that isn't food
Table cover down. Banner up. Plates, napkins, and cups staged where they're going to live. Trash can moved into the room and lined, with a spare bag underneath the first one so you can swap it without walking out.
Doing this on Saturday instead of Sunday is the highest leverage move available to a first time host. Setting up takes maybe twenty minutes, and on a Saturday afternoon twenty minutes is nothing. On Sunday morning, with food going and a clock running, those same twenty minutes come out of something that mattered more.
Sunday morning: perishables only
Ice, food, drinks into the fridge. That's the entire list. If you find yourself hanging a banner ninety minutes before kickoff, something got skipped the day before.
One genuinely last minute task is worth doing though. Set out the first eight plates in a visible stack, fan the napkins next to them, and stand one cup at the front. People copy what they see. A staged first place setting tells the room where the system is, and saves you from explaining it individually to nine separate arrivals.
What first timers always over buy
Decorations for surfaces nobody looks at.
The instinct is to decorate the room. In practice a watch party has exactly two zones that get attention: the wall near the TV, and the food table. Everything else is behind people's heads for the whole afternoon.
Skip the front door. Skip the bathroom. Skip the wall behind the couch, which is the single most decorated and least observed surface at any party ever thrown. Put that effort into the food table and one good banner in the sightline instead.
One last thing nobody warns first timers about: the party doesn't end when the game does. Somebody always stays for the late window. Keep a sealed package of plates and a bag of chips in reserve, because the second wave inherits whatever the first wave left behind, and a picked over table at 7pm is a sad thing to look at.
It's one extra package and it's the difference between the day trailing off and the day landing well.
Get your team sorted first, then fill in the rest from solid color tableware and party banners and signs. New customers get 10% off with code PARTY10.