This is 2017. Are you not putting all of your transactions in an ordered table in a database with creation timestamps? That information should not be lost and should be easy to figure out, in UTC. Figuring out the conversion of some other time/date is a solved problem.
There should never be a question of when some work happened if you're following sane practices.
I do huge ETL projects that live or die on the accuracy of our timing data. Give me date(time)s in UTC and I'm happy. Anything else? Pain.
This is 2017. Are you not putting all of your transactions in an ordered table in a database with creation timestamps? That information should not be lost and should be easy to figure out, in UTC. Figuring out the conversion of some other time/date is a solved problem.
There should never be a question of when some work happened if you're following sane practices.
I do huge ETL projects that live or die on the accuracy of our timing data. Give me date(time)s in UTC and I'm happy. Anything else? Pain.