Personal fork of of G6EJD's fine: https://github.com/G6EJD/ESP8266-NTP-time-on-an-OLED-with-WiFi-Manager

Developed on Arduino 1.8.3

Changes:

• Set ntp check to every 15 minutes
• Change date display to US Default
• quoted "Adafruit_SSD1306.h" include to pull locally.

Clone into your ~Ardunio directory, open in arduino IDE, compile, and install.

  cd ~/Arduino
    ~/Arduino $ git clone https://github.com/sboger/ESP8266-NTP-time-on-an-OLED-with-WiFi-Manager.git

Read about using WiFi Manager to setup.  AP mode, ip address, etc.