The best time to take action was yesterday. The second best time is today.
Tariffs are a long-term economic policy. It will take longer than 365 days to change consumer spending habits and onshore foreign businesses/production and rebuild domestic businesses/production.
Most countries have tariffed US goods for decades. The US tariffs on foreign goods will, over the long term, convince foreign nations to reduce or eliminate their tariffs on US goods (creating a more fair business climate for US businesses), and/or increase domestic production (creating jobs, salaries, taxes, etc).
We can't act like it's just too late to do anything about the lop-sided economic policies of decades-past, and we can't act like changing those policies today is nothing but doom. There will be a restructuring - a period of time to adjust - and then things will be fine over the long term. It just takes time and the political will-power to do so.