In short, think of prompts as a dynamic set of instructions that need to be maintained to control your user experience, more like the UI elements visible to the user in a given screen of your app, rather than as a one-time set of instructions to be locked at the start of the user journey.
Opt for deterministic outcomes, especially in the early user journey
With most online products, you finely control your user’s “day zero” experience with an intricately built onboarding flow, then you unleash them onto a magical blank canvas to do whatever they want. With an AI chat product, you probably want to keep the same philosophy and build deterministic chat outcomes for your users, especially in their first few days. But then what?
Should the AI bring up a certain topic or suggestion within the first five messages, or be prompted to a certain action on their second day? Should the AI change the topic at certain times to keep the user engaged? Is there a conversational ramp for the activation moment? Do you want to extract some info from your user during onboarding using a chat format to personalize the experience?