do I trill with the E or the G?
Just to mess things up a little bit: the answer really depends. You will need to tell us who the composer of the piece is. Bach and Clementi started their trills on the upper note, others (Schumann for example), started their trills on the principal note. With respect to Chopin, there seems to be a bit of a confusion.
Therefore, the question is not really E vs. G, but F vs. G.
Also, it often depends on the preceding note. If you start the trill on G#, you repeat the preceding note. Is that what you want? In your example, the trill looks like a passing (transient) trill, in which case you should start on the principal note.
The next question you need to answer is how long the trill needs to be.
Sorry, I hope you haven't ingrained the wrong trill yet
