Under "Soldering Time", you said "First solder a wire to the left and middle part of the potentiometer,...".
The picture 0629, shows that you have used a double wire and you have soldered one cord of it to the left part of the potentiometer, and the other cord to the middle part of the potentiometer.
There arises some questions:
1. Can a single wire be used and be soldered to both the left and the middle parts?
2. According to the web page you have linked (Beginners' Guide to Potentiometers), there are different wiring plans. Can you explain your reasons in wiring as you do?