If this report from China Times is to be believed (and this is usually a reliable source) then TSMC's 5nm testing is going very well and the first 3 customers have already been locked in - including AMD. According to the schedule obtained by China Times, AMD's 5nm products will be landing in early 2021 with mass production for 5nm scheduled in 2020.
AMD among first three customers to grab TSMC 5nm production capacity, NVIDIA missing from the picture
What is really amazing to hear in the report is that TSMC's 5nm yield has already crossed 7nm - which is quite the feat. This would mean that TSMC's 5nm will become viable sooner than expected and the transition from 7nm to 5nm can begin in earnest as well. The three customers that will be able to grab the first wave of production capacity are Apple, HiSilicon and AMD. While it is not surprising to see Apple get the first bite, it is interesting to see NVIDIA missing from this list - as I would have assumed they would be first in line to grab onto a process advantage (although this might be a questionable assumption considering they have yet to launch 7nm GPUs).