I deal a lot with time and time zones in the software I develop, and thankfully most frameworks make it pretty easy to manage. The rule tends to be, convert and store everything in UTC, and display it in the user's time zone in the UI, and call it a day.
In my previous post I talked about deciding what you give a fuck about and what you don't give a fuck about. But sometimes you realize you give a fuck about too many things still and you're still overwhelmed by the number of “threads” going through your brain. I know I was.