There is only 1 time acceptable - the ISO-8601 or equivalent time of publication in UTC, under the highest resolution you can get. Format to whatever you need o

There is only 1 time acceptable - the ISO-8601 or equivalent time of publication in UTC, under the highest resolution you can get. Format to whatever you need on display. Give an option to the user to adjust the timezone in which the user agrees with, by default the user's timezone, if you know it a priori. All your servers should use the same time server to sync time.