I was getting to you mate, hold on hold on. Its obvious that Izanami has prep time, if it didn't Itachi would have used it before the fight even started. You can go back and watch the fight, through out it, Sasuke continued to ask Itachi if his technique was ready. In chronological order Kabuto used Tayuya's demon flute before Itachi used Izanami, and Itachi was only able to use Izanami because Sasuke broke him out of DTF.
In a 1v1 fight, theres no way for Itachi to break out out of DTF, and the prep time for Izanami is longer than DTF.