People might initially be excited about your idea, but after 3-6 months of you building it and not hearing from you, that excitement might die down or be temper

People might initially be excited about your idea, but after 3-6 months of you building it and not hearing from you, that excitement might die down or be tempered. I'd say you need to do a couple of things. First, provide progress updates while building. Once you're done building and you decide to approach them again, re-iterate the pain points and benefits and try to build back that initial excitement. Also, read up on the principle of consistency in sales (for example pick up the book Influence by Cialdini). The idea is this: if you initially got a written and public commitment from the prospects, then those prospects will keep their word. They may also be less willing to flatter you given that kind of a commitment.