I want to create a niche fantasy world with an alternate calendar. Thoughts?

I haven't given this world a name yet, but I've always been fascinated by ancient timekeeping, but I want to create something unique. So far I have a year significantly longer than the Earth year, with 444 days. I want to divide it into a set number of months and have some kind of logical beginning point.<br><br>I'd also like to create a system for keeping track of years (like we use bc/ad). I'd like to use a similar system, but I don't want it to be specifically tied to a religious event. My first thought was to use a starting point (maybe an alignment of celestial bodies) that could mark the beginning of a massive change. Perhaps a time not too long ago in which the planet warmed.<br><br>Also, I've always been fascinated by how our months aren't in sync with the number of full moons we experience. So I'd like to have months that are perfectly in sync with that cycle. Thoughts? Thanks in advance.<br><br>(I'm not sure if this topic has been covered, please forgive me if it has)