처음 is used to indicate the first time you did something:
언제 그를 처음 만났어요?
When did you first meet him?
대학교에서 처음 만났어요.
We first met in university.
우리는 처음 만나자마자 좋은 친구 이었어요.
As soon as we (first) met, we were good friends.
한국에 방문이 처음이에요?
Is this your first time visiting Korea?
처음으로 저 식당에 갔을때 서비스가 나빴어요.
The first time I went to that restaurant the service was poor.