Before they are due:
Do all prep work for the meal, so it's either already cooking, or all you need to do is the cooking. No chopping etc, just adding things from bowls already prepared, all ingredients at least on the counter (measured out if possible) etc.
As much as possible, have the washing up done as well from that prep work (and if you have a dishwasher, run it in time to empty it and have it ready to fill with dishes from dinner).
Have the house warm and comfortable - even if there are doors firmly closed against the mess, clean the bathroom on the day and make sure it has a fresh towel and plenty of soap and loo roll, have the heating on ( or fire/stove lit if you have one), have the room(s) you will use neat and nicely lit (not the harsh central light but the side lamps glowing, candles lit in safe containers/holders etc). Know where you will put coats (empty the hooks beside the door and put your own coats on the bed for the evening, tidy 1 room so you can out coats on the bed....). A nice smell is good, but not essential (essential oils, nice smelly candle, etc) - clean and warm and welcoming are the most important.
Have drinks organised so you can swiftly offer something on arrival - and have something non-alcoholic for those who want it.
I also like to have bowls of crisps, nuts or other nibbles (eg. carrot sticks and a bowl of hummus, bowl of olives etc) out already laid out initially, until I can start to serve canapes or call them into the table if it is a formal starter. You don't need loads, but a choice of 2 can be nice.
I like to have the table set in advance - however formal or informal you want that to be.
I also try to have things like cups for coffee afterwards organised - they may stay in the cupboard if I don't have space to put them out while I am dealing with the main part of the meal, but I have checked they are clean, sugarbowl is full, jugs are ready to fill, and put the teaspoons into 1 cup rather than needing to rummage in a drawer - everything is in 1 place ready to go. The same for dessert items - I will put the plates or bowls together in a stack having checked they are clean and I have enough, any serving dishes or spoons are together with them etc.
And on top of all that, I try to organise myself well enough to build in a half hour to get changed and organised myself, (and even better an hour so I get to sit for 15 minutes once I am ready), before the guests are expected. It gives me time to relax somewhat and become the hostess not the commis chef, and also gives some leeway if some little thing goes wrong that I can fix it before others arrive.