Q:

Translating into English correctly (boiling down to Past Perfect usage matters)

This is the example of the text which needs to be checked out:

A: Is he a student? 
B: Yes, he studies at our university. He worked at our factory before
  he entered our university. Now he doesn't work.

Thus, I used worked instead of had worked. I did it because the process of working is a habitual, permanent state in the past and now it's not connected with the current situation: Now he doesn't work.
Since it's no longer valid I could use used to work as well as the above variant, but not Past Perfect.
As far as I understand, the process of entering the university is a reference time; some point or may be past time to which he worked at the factory.  
So, am I right? Is my understanding of the case correct?

A:

To my ear, "used to" is not well qualified by a before phrase or an until phrase.

Before getting an expensive speeding ticket, he used to drive like a madman.
   less idiomatic 
Before getting an expensive speeding ticket, he drove like a madman.
  idiomatic
He used to drive like a madman before he got a speeding ticket.   less idiomatic
He drove like a madman before he got a speeding ticket. idiomatic
He used to drive like a madman until he got a speeding ticket.  less idiomatic
He drove like a madman until he got a speeding ticket. idiomatic

