No estimation without experience. This works. New team? Needs time to get average velocity (burn down rate), about a month. Greenfield project? Need time to f

No estimation without experience. This works. New team? Needs time to get average velocity (burn down rate), about a month. Greenfield project? Need time to figure out how complex the domain is, again at least month, maybe two. Sure, you can still have deadlines, but keeping them without real data to base estimates on will require feature cuts (or more resources, but by the time it becomes clear it's too late).