"A did B until C did D" say "C가 D할때까지 A는 B했다." in Korean. The past tense of D is omitted in this case. If you want to express the past tense of D, say "C가 D했을 때 비로소 A는 B하지 않았다." I wasn't happy until I met you. 너를 만날 때까지 나는 행복하지 않았다. 너를 만났을 때 비로소 나는 행복했다.

(ㄹ/을) 때까지 — until 누군가 무언가 할 때까지 — until someone did something 저는 너를 만날 때까지 안 기뻤어요. — I wasn't happy until I met you. As you can see, the past tense is expressed with only last verb. I am still a beginner in Korean though, so I might be wrong. Though this is what I learnt using Daum.