You can start between 5 and 7 years of old.
Math homework just speeds up the learning process, but it really depends on your level of self-discipline.
If you what to take your math education to the next level, then teach it, but if you what to really get the best quality of tutoring, then learn from an older tutor with teaching experience.
Just trust the process, all you need to do is be ready to learn. In time both of you will fall into a nice routine.
The basics start from addition, subtraction, multiplication and division. This can start at age 5 to 7 years old.
The next is, Geometry, Algebra, Pre-Calculus, Linear Algebra, Trigonometry, Analysis, Number Theory, Combinatorics, Topology, Statistics and Probability, Set Theory, and a lot more.
Use someone who knows how to ask you the right questions to help you understand the concepts and who also knows how to simplify and how encouraging.