It should be unnecessary to point out, that from the very commencement of his training he should put himself under one of the best masters available. To spend a year or two under someone who is a poor teacher, because of the saving in fees, with the idea of spending the final months of training under a good teacher is not only false economy but absolutely throwing away money. Unless a singer is taught on proper principles from the very commencement, so much harm may be done in the year or two with a bad teacher that he will come on to the first-rate master in a worse state than he would have been at the start. Instead of finishing studies, the teacher will have to commence all over again from the beginning, with the additional difficulty that he will have to break down bad habits, instead of merely eradicating bad tendencies. Consequently, it will be seen that early lessons under a second rate teacher, so far from shortening the time of tuition necessary under a first-rate master may actually lengthen it.

Mackinlay, Malcolm Sterling. The singing voice and its training. G. Routledge, 1910.