You want the wave near your turret so he can't effectively get on you. Try not to push the wave when you are farming with q.

3Q>E Blade of the Ruined King is good into him, but nashor’s is better scaling wise. You can go Second wind for sustain, conditioning for tankiness, or sorcery with gathering storm and absolute focus for scaling. If you are confident then sorcery is the most optimal, but second wind is the safest. Focus on dodging qs. Cho’Gath has no gap close on you if he misses it. Don’t trade with Cho’Gath early. He hard wins short trades and he has much more sustain than you with his passive. Go Dshield and rush cull and boots asap. Try to be unpredictable with your movements in general so he can’t predict with his qs. You can cancel autos when last hitting and walk away so he is baited into q’ing when you last hit. Cho’gath can silence you so you can’t ult yourself and execute you with his own ult.

Do not trade with Cho'Gath early on. Even after six you aren’t going to do enough damage to outdo his sustain and pressure him unless he misplays. Sidelane is impossible for him once you get bork.