I just learned a hard lesson on this... In the back of my head, I was fairly certain that I could book dining for my entire trip once my 180-day mark arrived. Unfortunately, I tried to make my reservations online through My Disney Experience and it would only allow me to make them for the first day of my trip. So the next day, I repeated this mistake, and then again the next day and the next day, each time growing more and more frustrated that none of my top restaurants had any availability. On Easter Sunday morning, when I had 100 other things to do, I finally called the dining number. After waiting on hold for 20 minutes to reach a cast member, THEN getting disconnected and having to call back and wait another 15 minutes on hold, I finally reached a live person who said that the website isn't working for booking for your entire trip and that you have to call if you want to do that (up to 10 days from check-in). I am still kicking myself for not doing my homework on this ahead of time. Thankfully, she was able to find some openings that weren't showing up online, so in the end I was pretty happy with our plans. But it was a lot of unnecessary stress and it was my own fault