You should already be under way, penelope. Having moved a few times yourself you should be aware of that. First are the non-essentials - the things you can do without for a few weeks. Then there's the bits and pieces you dither over - if you are dithering then pack it. The aim is to have everything bundled up or boxed by two days before the move. Keep a couple of plates and a few pieces of cutlery plus bedding and clothing to get you through; these can be bundled up and tossed into the car boot along with any food you are taking with you when you leave. Remember that unpacking can be as much work (if not more) than stowing your stuff so label clearly what's in the boxes as it'll save you lots of time at the other end. Bon voyage. :)
[pen] ASAP, basically. We've moved in 1998, 2000, 2003 (twice), 2004, 2006, 2011, 2012, 2013. It doesn't get easier, as we have more stuff every time we move, but we are better at it. Twice we've done it at a week's notice, which adds to the fun! I suspect your move might be harder than most due to it being the Windy Miller's first, so good luck!