Where the rest of the world, for a time or for the entire delay, went with what WHO was saying, Taiwan was the only country I know that on December 31 assumed (without direct evidence and contrary to assurances) human-human transmission had happened and started screening, on plane, passengers arriving from Wuhan.
However the decision came to be made, the US did not act contrary to WHO assurances until January 17, still before WHO started admitting the truth. IMO, had Trump done this a month earlier that would have generated new howls for him to be impeached.
Shutting down travel to/from China effective February 2 was also done contrary to WHO's advice.