You should start way earlier in the process. If you get at that point you have almost no leverage and if you have to deal with people that don't listen to you.

You should start way earlier in the process. If you get at that point you have almost no leverage and if you have to deal with people that don't listen to you. In my own experience it's a two-fold process: - one is the ability of the engineering manager and the product manager to work towards a phased approach (smaller iterations means better chances at hitting the deadlines/estimations -if any) - the other one, by working closely with your stakeholders, so they have a good understanding of what's going on and the status of the team, effectively building a trust relationship.