A week or so before 180 days I will map out which parks I'd like to visit, based on the CLs available at the time. It will give me an idea of when I'll be in which park, and when we'll be at the resort. I think think about where I will want to eat in each park and decide which meal I want to have there, and maybe whether I'll want the meal to be early or late (i.e. a 10:30am breakfast, or a 4:30pm dinner) at any places I don't think will be a problem getting into.
Keep in mind that except for Epcot and/or any early closings for special events, the parks' closing times will larelgy be a function of expected crowds, and if anything they might make them a little later as the date gets closer because they're expecting more people to be in the park that day, which would mean longer waits so you might actually get to do less in that day even with an extra hour or two that night. If a closing time seems exceptionally early (like a 6:30 HS closing) then it's probably for a specific reason and won't change. I don't consider it to be a major issue if I planned on visiting Epcot because HS was closing at 8:00, and then then they change it to 10:00 later on... in most cases I wouldn't change my plans, either. There are some times when you just have to shrug it off.