Yosef Karo

“ Rem"a: Some say that there should be one set of tekiah-shevarim-teruah-tekiah for the kingship verses, and similar for the remembrance and shofar verses (Tur in the name of Rabbeinu Tam and Minhagim) , and this is the custom in these countries. The practice is to say "Hayom harat olam" after every series of blasts (Mahari"l) . Even on Shabbat, when there are no blasts, we say "Hayom harat olam" although not "Areshet" (Minhagim) . ”

“ Rather, they blow for him before he prays Mussaf and do not need to blow again (Kol Bo and Beit Yosef in the name of Orchot Hayim) .
סעיף ב
יחיד אינו מפסיק לתקוע בברכות ואפי' יש לו מי שיתקע לו: הגה אלא תוקעים לו קודם שיתפלל מוסף ואין צריכים לתקוע לו שנית: (כל בו וב"י בשם א"ח) :
592:3 Neither the shofar blower nor the community can talk between the sitting blasts and the standing blasts. (However, talking about the blasts or prayers is not considered an interruption) (Mordechai and Mahari"l) . If one spoke unrelated words, he does not need to repeat the blessing (Tur) . ”