How long will it take Tesla to start mass producing ventilators?

Elon Musk promised on Twitter that if there was a ventilator crisis, his company would spring into action and make them. It does take a while, though, to reconfigure factories. They do have designs. They are working on it. I would say a couple of weeks. In the meantime, Tesla has ordered a bunch of ventilators from China and is distributing them, which is great.