Build for customers, not for deadlines.
If you want to drive value as quickly as possible, set a timeline at then end of which you want to ship something. Focus relentlessly on cutting scope while still getting to the core use pain point. What you deliver may be a fraction of what you hoped for, but it’s driven by customer value and you released it “on time.” Rinse and repeat. It may take a while to get even your MVP out the door, but you will know that you’re focused on delivering customer value, and you will get a strong sense of your capacity and velocity.
If you want to ship an experience (rather than a feature) with a minimum set of functionality, consider scopeboxing. Determine what needs to be involved and derive clear product delivery milestones – user story mapping and slicing the work on both horizontal (user journey) and vertical (lightweight full-function through the stack) can do wonders to help here. Hold back on offering any ETAs to other stakeholders, internal or external – you’re not focused on time under this practice, you’re focused on scope. Relentlessly evaluate if you’ve gotten the scope of each milestone correct by questioning it and sketching out alternatives. Get each into a prospective user’s hands as they go live to see if it’s usable, used, and worth using.