Estimations are useful in high level discussions about feasibility and underlying technical complexities (like, is this a week or a month, and why?), and also to be able to make trade-offs between quick wins and larger investments. But estimating down to the story point or man-hour is a huge waste of everyone’s time and sanity.

What are you trying to do? Articulate your objectives using absolutely no jargon. How is it done today, and what are the limits of current practice? What is new in your approach, and why do you think it will be successful? Who cares? If you are successful, what difference will it make? What are the risks? How much will it cost? How long will it take? What are the mid-term and final “exams” to check for success?

I prefer not to manage the plan of a project in which I am also responsible for the content and the execution. This is a conflict in responsibilities. F.e. both project manager and solution architect.