Packing months in advance?
Repacking every week to make sure your under the baggage allowance?
We go out for dinner the day we finish work before a holiday, When the out of office gets turned on on the work email - thats when the holiday begins!!!
Then its check in - WH SMiths for the obligatory 20 womens magazines, several books and then for a mooch around the Duty Free shops, intending to buy everything but purchasing nothing, then getting to destination and spending 2 weeks wishing i had bought all the stuff I'd seen in Duty Free!!

What pre-holiday habits do you have???