The competitor won't stay idle for the next 5 years either. And that is probably the best estimate. Who know if that is going to happen.
My point is that China should prioritize what to focus on R&D first. In the short term, focusing on replacing the US parts won't contradict Chinese effort to achieve self reliance. Those parts are what China will need anyway for complete self reliance. Once you manage to do that, China can focus on the research for complete system. I read an article about how lithography is consisted of thousands of parts (don't remember the exact number), and no company in the world can make them all alone. Even ASML has to purchase the parts from other companies. If China is trying to make every by itself, I doubt China can succeed even in 10 years. But I suspect China is not doing that. China probably pursue similar path with building C919, buying parts where it still can't make it. The bad news is that I also read the US is trying to block the sale of the components to China. The good news is that those companies so far are resisting the blockade.