Just about every parent asks me this question. It is so difficult to answer because there is no set formula. So my honest answer: I don't know. Every student is different. There really are no easy fixes when it comes to learning differences.
(And I can't believe I said that-right?)
I like to think that teaching someone to read is like teaching someone to bake a cake. The first step is to assemble the ingredients and the tools you need to measure, mix and bake. With reading it's the same way. We need all the right ingredients and tools to get the job done. We need to identify sounds, blend them together, take them apart and mix them into new words. The issue for students with learning differences is usually, that they need different tools than the ones they are used to working with. Some students make steady consistent progress, while some progress, plateau, then progress, and plateau again, and others have a prolonged start, until they 'get it' and then they sail along. I find that most kids progress steadily until they are confronted with something that is difficult for them. And the difficulty is different for every child. It is important to remember, that giving your child the tools he/she needs to read and understand written language will help him/her in every aspect of his/her school work.
My honest answer.