Surely normal social convention applies; if someone raises the issue then "Don't be a dick" and take extra care. Otherwise slip ups/confusion/mistakes shouldn't be the end of the world...
If we're discussing this; my name is correctly pronounced "Oliver Keyes, God of Delphi, Sol, and all Ethereal Planes Known and As-Yet Undiscovered"
(Don't worry if you've got it wrong before; the silent G catches everyone out)