Based on some very recent reports on these boards, if you buy the DDE within the first few days of the month, your expiration date will be at the end of that month plus one year. If you purchase the DDE during or after the second week of the month, your expiration date will be at the end of the following month, plus one year. This is a change from earlier in the year. I purchased mine at the end of January and my expiration date is March 31, 2006. So they are being less generous lately with the expiration dates.
So, if you order on Sept 1st or 2nd, your expiration date would be Sept 30, 2006. If you order it the following week, your expiration date will be Oct 31, 2006. When you call to order it, ask what the expiration date will be since I'm assuming that you need the later expiration date.
Most people seem to be waiting 8 weeks to get their cards. If you order the DDE on September 1st, your cards will probably just make it a day before your departure date! If you have to wait a few days to order so that you can get the later expiration date, you'll be cutting it close and they may not arrive in time for your trip.
Given the tight timing, I would ask them to send a confirmation letter in the mail with an expiration date that is later than the last day of your trip. At least that way, you'll be covered in case your cards don't make it in time. Worst case, if you don't ask for a confirmation letter and your cards don't make it in time, you can call back before you leave on your trip and ask them to leave a letter for you to pick up at Epcot.
All this DDE stuff has been evolving, so it's a good idea to keep monitoring the DDE discussions on this board so that you'll be aware of any changes in policy around expiration dates, confirmation letters, card delivery times, etc.
