Where did you work before you worked here?
Where did you work before you work here?
Although subtle, adding "previously" makes for a much more eloquent sentence.
Correction: Where did you previously work?
1. adverb [usually ADVERB with verb, oft ADVERB adjective] Previously means at some time before the period that you are talking about. Guyana's railways were previously owned by private companies. The contract was awarded to a previously unknown company.
For more information: https://www.oxfordlearnersdictionaries.com/definition/english/previously