Determines whether one specified DateTime represents a date and time that is the same as or earlier than another specified DateTime.
true if t1 is the same as or later than t2; otherwise, false.
The DateTime.op_LessThanOrEqual(DateTime, DateTime) operator determines the relationship between two DateTime values by comparing their number of ticks. Before comparing DateTime objects, make sure that the objects represent times in the same time zone. You can do this by comparing the values of their DateTime.Kind property.