Booked Monsieur Paul @ 5:45pm on August 6 for NYE. I don't know if it was available before then. I don't think it was available at 180 days, since it's a prix fixe meal. I booked the rest of our ADRs for the trip at 180 days. Originally had the Countdown to Midnight at the Contemporary booked, but decided to do Epcot instead. We will do QS for lunch.
EDIT: Some of the special NYE dining was not available at 180 days, like California Grill, La Hacienda, etc. I don't remember exactly when it was released though.