If I were heading toward Tokyo but not neccessarily to Tokyo I would use へ. If I were going to Tokyo I would use に. That much I understand.
My question is whether this can be extended to time.
For example, If I wanted to tell Jim I will call him around 5 (presumably sometime between 430 and 6) I would say ５時へ呼ぶでしょう．However, if I want him to be at the phone at 5 then I would say ５時に呼ぶでしょう。to indicate that I will be calling at a specific time.
Do I have this correct, or is に always used in regard to time?