You can make dinner ressies 180 days before. OP, you might try to get ressies for free dining, you never know. I made some recently for that time frame and got what I wanted, though they were all resort dining (ex., Chef Mickey's, Ohana's)
*everyone*, on site and off, can make ADRs 180 days out from the ADR. guests staying on site can call starting 180 days from check-in and make them for up to the first 10 days of their trip, affectionately referred to as 180 + 10