I've been watching for the past several months as the new dates have appeared. It is usually the first week of the prior month. SO, if that holds true, it will be the first week of March. However, they did put up the hours for March in mid-January.
I hope they don't wait until March to post April's hours! We need to know so that we can plan our PS's at the restaurants! We're going the week before you guys.
Historically, disney has released park hours 60-90 days in advance of that month, but, I had seen as late as 1 month prior. we're waiting too. we go April 11-18th.