The key is be persistent. Keep checking the online dining a couple times a day and if you also would like, call the dining line as well. I just was looking for a 50's PTC dinner for our 1 and only DHS day for around 5pm (before Fantasmic) and could not find one for a couple of weeks. Finally about an hour ago I was able to find a ADR for 5:35pm for 4 people. So definitely be persistent and obsessive...something will bound to show up. Also, be flexible with your times too. Here is some

for you anyways in hopes something pops up before you leave.