Editing WoW:API GetGameTime (section)

=== WoW time API choices ===
For getting consistent times you have two basic choices: 1) use server or 2) use local client time.

Server time is good because all players in a realm will have the same time within more or less a minute accuracy, when you are on the same zone or instance server.

The client time APIs are good because you have seconds precision. However everyone's client times are different, as not only due people logging into realm servers from different time zones around the world, but their computers time may be off just like any other clock, or never been set, or even set with wrong time zone, all adding lots of variance. Despite this, using local time for most apps where a universal time between user isn't important, is the way to go if the app need to be sure its own time to not jump around.