Get Timestamp from ulog file

I am currently working on converting ulog files to time-aware kml and gpx files. It’s all working fine using this python script: ulog2kml · PyPI. However, you still need to enter the start time and date by hand. (YYYY MM DD HH MM) Is there a way to get this data from the ulog file? I have spent quite a bit of time trying to find something usefull but I have been unsuccessful. While the ulog file does have a start_timestamp variable, this is only stored in microseconds and only gives you realtive time (I assume since powerup) in minutes, seconds and microseconds. Hours however can’t be extracted from this variable. For my project I need the year, month and hour of the flight.
Does anybody have experience regarding that? Any help would be much appreciated!
Greetings Mathis