I agree with the previous posters. You've got plenty of time.
A few hints: Be realistic. You aren't going to work miracles in 8 days, but you can have most of the clutter picked up and the house clean enough for visitors. Get out a calendar and make a reasonable list of what you want to accomplish each day. For the next 4 or 5 days, work on decluttering 1-2 rooms a day. Don't just shift the stuff into a closet. Put it away in the correct place the first time. Be brutal... if it will eventually go into the garbage, put the stuff there now. Work in short increments of time (10-15 minutes, set a timer) and work quickly during that time. Work on the most noticeable items first... don't spend any time agonizing over what to do... just do whatever you see. Don't pull out more stuff than you can quickly put away... this is not the time to overhaul all of your closets or cupboards. Concentrate on public areas... kitchen, livingroom, bathroom, etc... I usually lock my bedroom when I have family over so I don't even worry about that room.
About 3-4 days before the get-together, switch over from decluttering to maintenance and cleansing. Keep up the decluttered level you've achieved but get the necessary cleansing done. Make a list for each day... again, stick to the stuff that is most noticeable and be realistic.
Leave the day before the get-together for food preparation, decorating, quick cleanup, and other last minute stuff.
Don't forget to enlist your family to help. My DH isn't the greatest at helping clean on a weekly basis, but is pretty willing to help when we've got a big group of people coming. Also, the kids should be cleaning up their own toys and their bedrooms, as much as possible. This is an excellent time (with Christmas coming up) to have the kids weed through their toys/stuff and throw some stuff out. At our house, we call it, "making room for Christmas toys."
One thing I like to use when decluttering is a laundry basket. I go in a room and throw everything that shouldn't be there into the laundry basket. Then I go through the laundry basket and put the stuff where it should go.
Here's a sample schedule of what my preparations might look like:
Day 1: Declutter Livingroom and Public-use Bathroom (in 15 min. increments)
Day 2: Declutter Kitchen and Masterbedroom/Bathroom
Day 3: Declutter Office and Kids' Bedrooms (wash laundry while decluttering bedrooms)
Day 4: Declutter any Remaining Rooms, Set Kitchen Oven to Self-Cleaning, Declutter and Clean out Refrigerator
Day 5: Scrub Public-Use Bathroom, Scrub Kitchen
Day 6: Wash Windows as needed,
Day 7: Grocery run, Vacuum, Mop all Rooms
Day 8: Cook, Clean Up as I Go, Wipe down Bathroom Counters, Mirrors, and Clean Toilet in Public-use Bathroom
Day 9: Relax and Enjoy Your Holiday!
I hope this helps!