It is Not permissible at all. You must pray and fast according to the timing of the place where you live. Allah (SWT) ordered in Quran all Muslims to abide to the time of start of fasting which is Fajr, and end of fasting as the start of the night .(Sura 2, Verse 187).
Those who claim following different timings are deviating away from the clear orders of Quran and the authentic orders of the Prophet Muhammad (SAWA).