AssemblyVersion equals build time
As documented , using an asterisk for build and revision numbers yields a build equal to the number of days since January 1, 2000 local time, and for revision to be equal to the number of seconds since midnight local time, divided by 2.
Thus a revision number can be turned into a build time with the formula:
AssemblyName an = Assembly.GetEntryAssembly().GetName();
DateTime d = new DateTime(2000, 1, 1, 0, 0, 0);
d += TimeSpan.FromDays(an.Version.Build) + TimeSpan.FromSeconds(an.Version.Revision * 2);