Please do read Exploiting AutoCorrect by Suzanne Barnhill, MVP.
It is important that your trigger for AutoCorrect not be something that you would otherwise type, even with a typo. This is because the insertion is instant and without notice. I am a touch typist and would not see such a replacement without careful proofreading (in the case of a text replacement).
Here is a link to my writing about AutoCorrect: AutoCorrect