As others have said, the operating hours are usually posted about 45-days/6-weeks in advance. Entertainment, including parade schedules, are usually added at some point after that, but often not until around the 30-day mark.
In terms of fireworks, it really depends on when DLR considers Spring Break to likely end. Last year, they presented nightly fireworks until April 19 (so two weeks after Easter). Easter is a week earlier in 2016 (March 27) and the main AP blockout period is the week before and after Easter. My guess is that nightly fireworks will at least run through the entire week after Easter (April 3) and possible for one more week past that (so ending somewhere around April 10). After that, they're likely to only be presented on weekends (Fri to Sun).