I'm afraid I don't have an expert opinion on how long it takes for the process to occur. I haven't done any studies of past tax reforms to see how long it takes from the start of a review to the end of a review. Having said that, I think there still is merit in constantly looking at the tax system and trying to evaluate efficiency, simplicity, economic impact, and whether it's achieving the goals that the government has.
I'm sorry that I don't have a specific answer to your question.