It is disliked to start a voluntary prayer after the Mu’adhdhin has started to say Iqamah for prayer, whether that is a regular sunnah, such as the sunnah of Subh or Zuhr, or anything else, and regardless of whether he knows that he will catch up with the rak`ah with the Imam or not
وَحَدَّثَنَاهُ عَبْدُ بْنُ حُمَيْدٍ، أَخْبَرَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا زَكَرِيَّاءُ بْنُ إِسْحَاقَ، بِهَذَا الإِسْنَادِ مِثْلَهُ .
A hadith like this has been reported by Ishaq with the same chain of transmitters.