When should I stop teaching?
Once you start, you will never stop teaching, all the best musicians teach – they always have time to impart their knowledge. If you are ever in the position where you can do this for free because of secure finances, good for you and thank you!
For what it’s worth, if you are not 100% certain about making a difference through teaching and wanting the highest standards for your pupils – don’t do it. Think about what you’d want from a teacher and if you cannot do it, let somebody else take on the work. There’s nothing worse than uninspired, poor teaching that turns off potential musicians from doing something they love.