Day Zero is the minimum set of tasks a user must complete before they realize the full value of your product. Customers that don’t reach Day Zero are more likely to churn because it is harder for them to see success.
I’ve been thinking quite a bit about churn recently and how it relates to customer support. This article on the Intercom blog broke down a pretty interesting concept—Day Zero.
The underlying idea is to identify a handful of actions that are crucial to a customer’s success on your product or platform. Once customers complete these actions, they’re much less likely to churn. Once you’ve identified these crucial actions, your goal is to get each new customer to complete them as quickly as possible after signup.

For anyone interested in building products and minimizing churn, I’d highly suggest giving this article a read!