DH printed the Disney countdown signs from their Facebook page.
https://m.facebook.com/media/set/?s...efsrc=http://www.google.com/&refid=9&_rdr#_=_
When we hit a milestone, like 1 month away, we took a picture of our son next to the sign.
The signs are actually designed to be posted on your Facebook timeline, so there's that option, too.
About two weeks out from the trip, you could introduce something like an advent calendar with a small present each day. Order a lot of pins in expensively from eBay and give them one each day. The first or last day of the calendar, the gift could be a lanyard for pin trading.
Make Mickey shaped cookies. Decorate each with a number 1-7-- one such cookie for each person in the family. Eat a cookie each day after dinner as you talk about your trip.
Make a box with a small gift for each day leading up to the trip. Make the gifts things they will need on the trip like cheap sunglasses, poncho, things to do on the plane/ drive, cheap glow-in-the-dark stuff from dollar store for parade times, autograph book, sunscreen stick, new tee-shirt with fave characters, certificate to download fave Disney movie. This doesn't have to be expensive-- just wrap up things you would buy anyway to pack for the trip. Or set this up as a care package to open right before you leave or when you get to the room.
Look on Dis-signs on this site. People will make you little signs, calendars,etc.
Sign up for Fairy God Mailer on this site. Someone will agree to send your kids a postcard from WDW. You agree to pay it forward for someone else.