It depends on your child’s foundation. It depends on how “teachable” your child is.
We cannot promise you an overnight miracle or boast a magic formula of “See astounding results in 3 months!”
A weak foundation means that a lot has to be imparted. And that takes time, depending on each child’s learning aptitude and attitude. However, there will be progressive improvement — step by step.
A “teachable” child is willing to pay attention during lessons. He will also apply whatever is taught dutifully and purposefully. This child should see a significant progress within a semester.
For a teachable child who only needs to grasp the techniques and master the skills, he/she will definitely see a marked improvement within a semester.
However, a child who needs to foster a teachable attitude requires more time as we need to “plough the soil of his heart”. Together with you, we will persevere for the positive change in your child’s attitude. So long he/she is willing to sow the seeds of effort, surely, there will be progress. (“In hard work there is always something gained.” Proverb 14:23)