The phrase "most sooner" is not a common phrase in English, and it is not a standard grammatical construction. However, if we were to transcribe it phonetically using the International Phonetic Alphabet (IPA), it would be /məʊst ˈsuːnə/. This transcription reveals that "most sooner" is pronounced with a long "o" sound in "most" and a long "u" sound in "sooner". Despite the phonetic clarity of this transcription, it's unclear how this phrase would be used in a sentence or what it would mean.