Do I need to know the time phrase before I speak?

No, but you need it before the verb, which is a much smaller window. Most speakers find the phrase as the sentence forms, and that is early enough: the anchor usually comes before the main verb. If it arrives after, finish and restate the window in a short follow-up. The one case that needs planning is a story with several events: fix the order of the anchors first.

One shortcut that saves the decision entirely: borrow it from the question. A question in the past simple, such as Where did you go?, usually expects the same form back. A question in the present perfect, such as Have you been there?, leaves the window open, so the same form answers it. Answering with the form you were asked is not always the best choice, but it is almost always a safe one, and it costs no thinking time.

Present Perfect or Past Simple? A Rule You Can Use While Speaking →