Also, I think just because it's circulating doesn't necessarily mean that there is a good chance of it being brought to other countries. If it really started off in a wet market, I can imagine that the people who are most susceptible to catching the virus initially are not those who can afford/have the opportunity to travel.
If I'm not mistaken, August is about when people return from summer holiday, and there aren't really holidays until Chinese New Year. There a week of holiday in October for National Day, but people typically travel back to their home town instead of overseas.
It feels possible that the virus could be limited to just transmission within China for a while, which gets spread with every festival between August and late December/January, eventually reaches a critical mass and spread to the rest of the world with people travelling due to Chinese New Year in early 2020.
I honestly don't think I'm right, and you probably spotted logical flaws in the example I have given above. I just want to point out that the problem is extremely complex, and even the facts that you have pointed out are only a small part of the whole picture that just happen to support your views and arguments.