I Think the 6.5 iPhone X will launch accordingly in September, assuming that they have enough units manufactured during that time frame without constraint, it’s the 6.1 LCD iPhone that was rumored to possibly launch later in October due to delays.
No reason for Apple to delay availability unless there's a manufacturing or design problem. This year, Apple has chosen two OLED suppliers and two thin-bezel LCD suppliers. TrueDepth component suppliers have had a year to improve yields.