Your post is probably going to be moved to the Restaurant board, but I'll try to answer part of it.
You can make Advanced Dining Reservations (commonly called ADRs) six months to the day in advance. If you are staying onsite, you can call six months from your arrival and make ADRs for up to 10 days after arrival (commonly called 180+10). Not all of the availability is open to the +10 ADRs, so if you don't get what you want during the +10 period, you'll probably have better luck calling exactly 180 days out.
For many of the premier restaurants, you need to call very early to get the ADR times you want. Many people call at 3 months and find they can't get the restaurant they want, on the day they want, at the time they want. If you're calling for a very popular restaurant like Le Cellier, you may well not be able to get anything three months out.
Cinderella's Royal Table (AKA: Cindy's or CRT) is a special case. On the restaurant board there is an entire thread on CRT strategies. Basically, you have to call at 6:59 AM Eastern time exactly 180 days out, and be very quick working your way through the system. If you want CRT, read and heed that thread.