Start with the time you want to serve.
Work backwards, thinking how long things need to cook for and write a master list of when you need to do different steps. Be as detailed as you can be, include what pots/trays you need (so you don't need the same one for 2 jobs at the same time - 2 jobs at different times is fine if you have a washer upper), what each step is (is it "season with salt and pepper" only, or "season with salt/pepper, thyme and orange juice"...).
You may not need to refer to it on the day - but it makes it less daunting to have thought it all through once, and also means you can come back into the kitchen to do something and just tick it off, or if someone else comes in to offer to help you can just give them the next thing on the list to do.
Do some prep on Christmas Eve.
Peel veg and potatoes and either soak in cold water (potatoes, carrots, etc) or airtight plastic tubs (parsnips, onions) - sprouts can be either.
Make your stuffing.
Make your gravy.
Perhaps make your dessert/starter.
If not already made (can do this today!), any flavoured butters you need - for under skin of turkey to keep it moist (we like garlic, salt/pepper, thyme, rosemary and some sage in this), to toss over carrots (garlic, S/P, oregano and thyme), or sprouts (pepper, parsley - the bacon pieces already tossed in make it salty enough).
All meat is better if it has rested after roasting before carving - turkey can rest for up to 2 hours happily, but if you plan for 90 minutes, cover with 2 layers of tin foil and then a folded over large (clean) bath towel, it will be perfect.
90 minutes is plenty of time also to cook roasties and other veg, heat gravy, and still get a glass of wine and chat with guests.
Par-boil roast potatoes for 10-15 minutes (drain pot of cold soaking water, pour over boiling water and simmer gently for 15 minutes) then drain. Put your roasting tray into the oven before you drain them. Add the fat to the pot (olive oil, goose fat, whatever you are using) and let it heat up, put the lid back on the pot and give it a good shake to cover the spuds with fat. Put the potatoes onto the hot tray and roast for 45 minute to an hour.
I find it really helpful to have the sink full of hot sudsy water while I am doing my prep and cooking, to be able to wash as I go along. I might need some pots/trays again, but it also clears space to work in.
I also run the dishwasher after Christmas breakfast, whether it needs it or not, so that there is plenty of space for things as I am working and when we finish the various courses (dirty dishes are not getting in the way of plating up the next course).
Having a stack of clean tea towels is also useful - you can easily assign someone who offers to either wash what's sitting there, or to dry things and out them away. I find stopping to wash a pot in the water while I work is fine, but drying breaks my concentration, so I will leave it dripping on the drainer, so someone who comes and clears that away is very helpful!
(Kinda related to that last - I tend to do big meal prep wearing an apron to avoid splashes, and having a hand towel hanging off the strap at my waist - so I can dry them regularly as I wash them after handling raw meat, or smelly things or messy things, or after I've washed a pot or whatever. That is a separate hand towel to the general use one that always hangs in the kitchen anyway). The need to regularly wash hands is another reason why the basin of hot sudsy water is useful! You will need to refresh it occasionally (it will get dirty, and/or cold) so make sure you have plenty of hot water available.
As the cook, you will need to open a bottle of wine for a good slug in the gravy, and it is important to quality control that by having a glass to check. But only a small glass so you don't lose track of what you're doing.
Quick tips for veggies other than ones you mention (and not necessarily needing the cooker):
Peas - buy frozen petits pois, pour into a pyrex bowl/spare pot when turkey goes into the oven to thaw. When you are almost ready to serve, boil the kettle and pour onto peas. I don't even turn on the heat on the cooker, but if you have a lot, you might find that useful especially if they are still a but frozen - but they only take a couple of minutes to be ready.
Spinach - baby leaves, open bag, pour into colander draining over sink. Boil kettle, slowly pour all over the leaves and let it drain. Perhaps use potato masher/large spoon to press excess water from leaves. Perfectly wilted spinach.
We don't do a starter, we do a tray of M&S party food (or maybe a few if there's more present) roughly when the turkey comes out (so potato tray is probably heating up but veggies are not yet in the oven).
But plating up some smoked salmon cold be delegated to someone,
Or a large pot of soup to reheat shortly before serving could be made on 23rd or 24th.
We like a cheeseboard, we usually need time to let the roast settle anyway, but I get the cheese out of the fridge around the time I am dishing out so it can come up to room temperature.
Similar with any cold desserts - if something like a tart, cake, trifle... does it need to come up to room temperature or should it be served straight from the fridge/freezer?
What "sides" do you need for other courses - starters, cheese, dessert as well?
Bread and butter for salmon or soup, marie rose sauce for prawns, ….
Grapes or dates or figs or chutnies for cheese, and biscuits/crackers
Whipped cream, ice cream, fruit coulis, chocolate sauce, brandy butter.....
Milk, sugar, cream, chocolates, mince pies for tea/coffee?
Note: You DON'T NEED TO DO EVERYTHING.
A relaxed hostess who puts a hot and tasty meal in front of her guests with a smile is a good hostess.
A hostess who stresses herself to the hilt while aiming for "perfection" and everything that is "traditional" and "what everyone else has" - is heading for a meltdown and your guests won't enjoy that nearly so much.
Pick what you are happy to do, that you know your guests will enjoy, and is within your (and any helpers available) capabilities. Unless you want to practise this weekend, don't try things you have never done before - buy it in, leave it off the menu, ask a visitor to bring their speciality with them...but don't stress and panic about it all.
I also find, as the kitchen can get very hot and steamy on Christmas Day, having some air coming through (an open window somewhere) and getting out to put the bins out or something to get some actual fresh air can make a big difference to being able to cope with it all. Have a glass of something cold available to keep yourself hydrated (non-alcoholic, so in addition to your glass of wine) - whether you prefer water, sparkling water, squash, or a fizzy drink.
And to dress in lighter clothes for cooking - apron cover can still mean nice clothes, or you can build in 10 minutes to change before serving into your Master list - but don't get too hot yourself.
Sorry, that's a lot longer than I intended..