It takes 7+ years to bring a new factory online. more to get all the kinks worked out and at full production

Not to take away from your point but they also have to

• product is at par with the previous alternative in terms of quality
• your supply chain is willing to shift to your new product
• healthy supply of workers OR
• good automation in your production line (automation supply should also be sourced from within the country)

Once you have created this factory (which needs to be subsidized by the government in order to compete with the foreign product), we then apply targeted tarrifs so that people can slowly shift to the homegrown product. Doing all this can takes decades of careful planning.

Tarrif is not an ON/OFF switch which Trump thinks