Flashing ESP8266 ESP-12E/12F I'm pretty new to Arduino programming and i'm trying to connect this ESP8266 module to my FTDI programmer but constantly getting this error on my ARDUINO IDE:  esptool.FatalError: Failed to connect to ESP8266: Timed out waiting for packet header.
My guess is that its not in flashing mode and that i have to connect GPIO0 to ground or sompthing else.
On my version of this "Adatper" adapter the io pins were not connected. I patched io 0 to the esp-01 like header, to be able to put the ESP in bootloader mode. On the picture you see a paperclip jumper connecting io 0 to ground for flashing mode. 

Back then I could leave the jumper connected, because the esp8266 run the sketch after upload. In new versions of esp8266 arduino boards package the esptool hard resets the esp8266 so it returns into flashing mode. This can be changed in platform.txt.

I recommend you to buy an esp8266 dev board with USB (Wemos, NodeMcu and similar)