I’d say less than a week. Capitalism is something that we have to wake up and make happen every single day. How many days worth of food does the average person have? Definitely not 45 days. People would have to start self-organizing within 2-3 days, and in doing so, they would actively make something that isn’t capitalism, which directly challenges those in power.
This is why every time there are emergencies or protests, the media is obsessed with “looting.” If there’s no food because of a hurricane or whatever, it is every single person’s duty to redistribute what there is equitably. The news and capitalists (but I repeat myself) call that “looting,” even when it’s a well-organized group of neighbors going into a closed store to distribute spoiling food to hungry people.
Rebecca Solnit writes about this in detail in A Paradise Built in Hell. It’s really good. She’s an awesome writer.