Choose a time-scale

Common ones:

• machine
  • unix timestamps
• human
  • gregorian calendar

Choose a data-type

A 'date' is not a time-stamp, is not a number of milliseconds

Stop!

• Using points on one timescale to model ranges on another
• Thinking that "UTC" will solve your modelling problems

Your language/database's date/time data-types ...

...are broken; don't use them.

UTC ...

... is not a time-scale.