You can use -면 if the event in the when-clause didn't happen yet. There're some exceptions to this, but it's easy to figure out which one makes sense. When I go to the park, I bring my dog with me. 전 공원에 갈 때 개랑 같이 가요. - 전 공원에 가면 개랑 같이 가요 doesn't make sense since your dog isn't in the park. - 전 공원에 가면 나무 밑에서 쉬어요(When I go to the park, I rest under the tree) makes sense. When I'm sleepy, I want to sleep. =p 전 졸리면 자고 싶어요. - 전 졸릴 때 자고 싶어요 is also possible. When I was young, I liked corn. 전 어릴 때 옥수수 좋아했어요. When winter comes, I will be sad. 겨울이 오면 전 슬플 거예요. When I come home, I'm going to eat. 집에 가면 밥 먹을 거예요. When I graduate from school, I will go to France. 저 졸업하면 프랑스로 갈 거예요.

Actually both translations work only for the zero conditional.^^ For example, When I go to the park, I bring my dog with me. = 내가 공원에 갈때 난 내 개를 데리고 간다. = 내가 공원에 가면 난 내 개를 데리고 간다. *The structure of the zero conditional. "When + subject + verb(the present tense) ~ , subejct + base form ~" or "When + subject + verb(the present tense) ~ , subject + will + base form ~" In here, WHEN is translated as "~면" or "ㄹ 때" in Korean. All sentences you put as example are translated in the both ways except for the second sentence. ^_______^