The perfect middle/passive of the verb xo/w is first attested in the infinitive in Thucydides (2.102.6), Xenophon (Cyropaedia 7.3.15), and Deilochus (FGrH 471 F5a). The corresponding participle, here in the masculine nominative singular, is perhaps cited here from Plato Comicus (fr. 183 Kock, now 199 K.-A., quoted in Plutarch's Themistocles).
For other forms see e.g. Polybius 4.40.8 and later historiography (Diodorus Siculus, Plutarch, Arrian, Pausanias).