On Windows, filenames do not like some characters (including : and +), so this is a quick way to get a timestamp into ISO8601 format that is compatible with filenames.
TimeStamp := Now();
StartIso8601String := DateToISO8601(TimeStamp, False).Replace('-', '').Replace(':', '') // https://en.wikipedia.org/wiki/ISO_8601#Time_zone_designators
It Depends on the [WayBack] System.DateUtils unit which had the [WayBack] DateToISO8601 function [Archive.is] added in Delphi XE6.
A poor man’s solution (that skips timezones altogether) is this one:
FormatDateTime('yyyymmdd''T''hhnnss''.''zzz', TimeStamp); // note quoted T and ., as otherwise they will be expanded.
–jeroen