Right, that makes sense.

If your project requires an ESP as well as Bluetooth, you might want to hold on the final design and migrate it to the expected-soon ESP32, which supports Wifi as well as BLE.

I'm wondering, why use an Arduino at all? Do you need more I/Os than what the ESP8266 12E has?

I'd stumbled across Neils book a few days back. Its absolutely amazing, isn't it? Quite an exhaustive resource.