‘Tis the season, as they say. This is an age old question for all piano teachers. The dilemma is not how early you start, but how many pieces are you are going to teach? My students play several venues over the holidays including a studio recital, so they have to have a variety of pieces ready to go by early December. They begin in August, as some (the more advanced students) need to have as much as 20-30 minutes of repertoire ready to go. If we waited until November to begin, then that would be all they were playing for weeks (and other events in the Spring would be compromised). I prefer to start with a single piece in August and just add it to their other repertoire. This way, it is not overwhelming to get the volume of pieces ready on time. If you are not having any programs, then there is probably no reason to start before December and just enjoy a few weeks of saturated Christmas music. Either way, you will have happy students and parents. Oh, and just in case you haven’t thought of this, even my students who do not celebrate Christmas get into the swing of things. They love the pieces and different arrangements and beg to play more. So, how soon is too soon? Judgement call on your part.
What is the significance of playing and identifying chords? From the very first year of study, students learn how to play a triad and probably know how to identify several in root position. HOWEVER, when the chord is in an inversion or spread out over the treble and bass clef, it becomes much more difficult for a student to recognize. I think the best way to prepare students from the beginning is to learn chords and their inversions along with scales. Once the student realizes how the chords works within the scale (key), reading and playing passages start to make sense and are much easier to master.