I enjoy hosting- this might sound crazy-nerdy of me, but the prep for it is half the fun 🙂
First thing I would do is make lists, it may seem like one more thing to do, but it’s actually calming to see what you have to do on paper rather than trying to keep 12 ‘to do’ things in your head and feel like you’re forgetting something.
First list is the menu- even if you’re still thinking up ideas and the list is incomplete.
Second, start making a grocery list from your menu- and add to it as you finalize your menu. Divide it into things that can be bought in advance (like dried spices and packaged food) and things that need to be bought fresh closer to the dinner (like produce, fresh spices).
Make a list of household chores to do- I’ve been hosting for years and years and I’ve learned as much from past mistakes as past successes. Don’t over-burden yourself doing cleaning or organizing the morning of that could’ve been done a week before, you don’t want to be up before dawn washing floors and bringing up extra chairs from the basement or garage that need a layer of dust cleaned off. Do as much as you can in advance so you’ll have very little of this to do the day of or even the day before- ie a bathroom you cleaned from top to bottom 5 days before will only need a basic sink-&-toilet super fast clean closer to the date.
If the budget allows for it, a few extra touches will make things more festive and make you feel more in your hostess-ing zone- Dollar stores are great for this. A few holiday themed hand towels for the bathroom (if you don’t already have them), a sprig of something fresh smelling like a pine bough. A little surprise bag for each child with holiday themed things to do (again, think Dollar stores, you can do this for under $10 per child- Christmas colouring books or activities etc)
And finally- this is something it took me years to realize! Make sure you take time for you. Early years of hosting I’d be a whirlwind of trying to be superwoman, only to be exhausted and feeling like I looked frumpy and harried by the time the actual event came about. Be sure to share these lists with your Darling Husband, teamwork, teamwork, teamwork. Don’t try to make absolutely everything from scratch. I know you have to be extra careful with your FIL’s allergies, but don’t be afraid to cut corners in some areas. Choose a signature dish or two to make from scratch and a few of the sides, but for other stuff buy ready made, checking the labels re gluten-free. For example, I’d make the main meat entree plus a vegetarian special of mine, Spanakopita Streusel from scratch. But I suck at pie crusts so unless a local fam member was doing desserts, I’d buy a couple of Farmer’s Market pies. I also buy fresh ready made veggie and fruit trays from our grocery deli.
And even though this might sound like something you don’t have time for- take time out of your busy morning to have a shower or bubblebath, do your make-up (if you normally do make-up) hair etc. Obviously you won’t have time to fuss over your appearance for ages- but taking even a half hour/45 minute chunk of time for yourself will make you feel pretty and festive. Your Darling Husband and in-laws can hold down the fort while you take time to get ready. After all, if your Darling Husband was in the kitchen and dining room for ages getting things ready, you wouldn’t begrudge him half an hour to shower and shave and put on fresh clothes to feel good greeting guests/ enjoying hosting, would you? So don’t begrudge yourself either! This also helps you to relax before the guests arrive so you’re less frazzled and more festive. Plan in advance what you’re going to wear- whether it’s a new dress or an old favourite, accessories etc., so that all you have to do is slip into what you’ve already laid out in advance. Again, if the budget allows for it, pampering yourself with something new is a nice little indulgence- anything from a new haircut or a gel manicure or new perfume or (more reasonably budgeted) cute holiday earrings (the kind that are only a few dollars with little red and green balls or Santa-hat wearing penguins 🙂 or a new hair accessory (clip, scrunchy etc). It’s nice when there’s $$ to splurge, but it can also be done for only a few dollars.