There aren't any rules that I know of. Modification works best. For example, if today is Thursday, and I want to refer to two days ago, I'd say, on Tuesday past, or this past Tuesday, or two days ago Tuesday. As for years, if it's November, and I want to refer to October of this year, I'd use: last month, or in October (of this year).Originally Posted by Unregistered
Relationships in time and space are deictic; e.g., this apple here versus that apple over there. In native American languages, there is even a deictic pronoun, a single word, which in English takes up an entire phrase to express; i.e., the person who is not here with us as we are speaking.