You have to disbelieve the client. When a mid-sized client tells you “this is the solution, when can we do it?” it’s not the same as a large corporate client telling you that they’ve selected a software package and now need implementation advice. The latter have both the expertise and experience to have made a rational decision and you can feel safe moving forward. The former has probably fallen for somebody’s sales pitch, or is engaged in what one of my mentors called “management by magazine.”