For now, I'd get everything down from the loft and have a good clear out if you haven't done already. Also, go through your cupboards, wardrobes and throw away anything you don't want to take with you. Also, if you're taking your appliances, now would be a good time to pull them out and give the floor underneath and units either side a clean, as this will save time on removal day.
Personally, I wouldn't start packing until a couple of weeks before unless your sure you don't need something. Last time we moved, the completion date came up very quickly - we found out on the Wednesday we'd be moving in six days, had our packing boxes delivered after work on Friday and everything got packed up over the bank holiday weekend ready for moving out on the Tuesday. We didn't have any garden stuff to deal with though.