A method comprising: at a text-to-speech, TTS, system , receiving a real-time streaming text string having a starting point and an ending point; at the TTS system, accumulating a first sub-string comprising a first portion of the text string received from an initial point to a first trigger point, wherein the initial point is no earlier than the starting point and is prior to the first trigger point, and the first trigger point is before the ending point; at the TTS system, applying a punctuation model of the TTS system to the first sub-string to generate a pre-processed first sub-string comprising the first sub-string with added grammatical punctuation as determined by the punctuation model; at the TTS system, applying TTS synthesis processing to at least the pre-processed first sub-string to generate first synthesized speech; and producing audio playout of the first synthesized speech; while applying TTS synthesis processing to the pre-processed first sub-string to generate the first synthesized speech, concurrently accumulating a second sub-string comprising a second portion of the text string received from the first trigger point to a second trigger point that is after the first trigger point and no further than the ending point; applying the punctuation model to the second sub-string to generate a pre-processed second sub-string; while producing the audio playout of the first synthesized speech, concurrently applying TTS synthesis processing to the pre-processed second sub-string to generate second synthesized speech; and producing audio playout of the second synthesized speech. at a text-to-speech, TTS, system , receiving a real-time streaming text string having a starting point and an ending point; at the TTS system, accumulating a first sub-string comprising a first portion of the text string received from an initial point to a first trigger point, wherein the initial point is no earlier than the starting point and is prior to the first trigger point, and the first trigger point is before the ending point; at the TTS system, applying a punctuation model of the TTS system to the first sub-string to generate a pre-processed first sub-string comprising the first sub-string with added grammatical punctuation as determined by the punctuation model; at the TTS system, applying TTS synthesis processing to at least the pre-processed first sub-string to generate first synthesized speech; and producing audio playout of the first synthesized speech; while applying TTS synthesis processing to the pre-processed first sub-string to generate the first synthesized speech, concurrently accumulating a second sub-string comprising a second portion of the text string received from the first trigger point to a second trigger point that is after the first trigger point and no further than the ending point; applying the punctuation model to the second sub-string to generate a pre-processed second sub-string; while producing the audio playout of the first synthesized speech, concurrently applying TTS synthesis processing to the pre-processed second sub-string to generate second synthesized speech; and producing audio playout of the second synthesized speech. <EOS>