Is it true that it is not permissible to pour milk before coffee, based on a hadith or a narration that says: "Change with it, but do not change it," and was coffee present during the time of prophethood?

There is no شرعي (Shar'i) evidence prohibiting serving milk in a cup for something else to be added to it. In fact, it is established in the Sunnah that water was added to milk, as in the Hadith of the Hijra (migration). As for the saying "غيروا به" (change it with it), it has not been found. Furthermore, coffee, in its commonly understood meaning today, did not exist during the era of prophethood, and the word "قهوة" (qahwah) is one of the names for Khamr (intoxicant/wine).