As someone recently invited to a Disney wedding, I'd include that Disney rooms book up to a year in advance on the save the date along with what specific days you have rooms blocked for. It may seem odd, but a Disney Wedding is a very different experience than a regular wedding. With only the day or two surrounding the wedding blocked (at least at the wedding I was invited to), anyone that wants to stay for more than just the wedding itself will have a really hard time finding a room available for their full stay. I am the only guest other than the bride/groom that has a fair bit of Disney experience and knew that I needed to book way out, but even 5 months out (when I got the save the date) I wasn't able to get a room at two of the three options, and ended up picking a non-blocked room because my only option left was GF at over 500 a night even with the discount. I'm good friends with the groom's sister, and let her know to book her room asap if she wanted anything and she also ended up having to go for a non-blocked room at another resort because there was no availability at the GF when she looked two days later. I am just imagining a lot of frustration from the guests that book in the few weeks before the wedding being unable to find an on property room.