People ask me how far out to plan, I tell them it is never too early. If you can start 8-10 months out, or more, this is great! A big reason is if you are planning to go to Cinderella’s Royal Table in Cinderella’s Castle at Magic Kingdom or Chef Mickey you need to make these dining reservations 180 days out first thing in the morning. Yes, I said 180 days. You might get lucky after the 180 days but not usually.
Do not think you cannot plan a trip with little lead time, you can and still have a great time! Never give up trying for the reservations they do sometimes open up as you get closer to your vacation date. I will be happy to try for you, as I know it is so important.