Latest PoD that doesn't involve a period of more than a hundred years of Christianization that would probably be silly is during the 1110s. The Turkish identity didn't really get formulated until the fall of the Byzantines. Until then, almost all literature was still in Greek and the lack of real Muslim construction or scripture tells us that the plateau was still only superficially Turkish. It was only with the rise of Suleyman in 1197, the appearance of the Sufis, and a general cultural revival in this area due to the end of any Crusader or Byzantine tensions that allowed the Turks to solidify their hold over the area. Until then, a Byzantine army can retake the area, and not suffer any real problems with a muslim population.