We'll have already moved on with our lives twenty years down the line, but we visit the site and see PTA with 30,000 posts and nowhere near a climax. xD
I think this is a problem most RPs with set dates run into. My best advise for you: use timeskips, and use them often. Sure, have dates where players can interact and do things. But if you're pressing for specific dates in a year-round schedule, do some timeskips. Maybe have a certain date you can play out each week, or month, and then jump forward. This can be done a few ways, I think.
If playing out a week really takes a year, play out a few days, then timeskip forward a few weeks, or maybe even months, if need be. Or play out one or two days, and skip to maybe halfway to an important event, play it out a bit, and then skip again to a day or two before an important event to build up to it. That should maybe work.
My other suggestion is to axe the timed dates or simplify them. Maybe do in a month what could be done in a year. If that doesn't fit with the RP, however, go with timeskips!