I get this a few times, but my conversation goes something like: Peter) how long will it take to do "an action that you don't know how long it will take" me)

I get this a few times, but my conversation goes something like: Peter) how long will it take to do "an action that you don't know how long it will take" me) I don't know, at a complete guessminate X weeks Peter) ok, you can do it in X/2 weeks then me) I'll need to triage the request and understand the requirements then at a guess it "may" least Y days to investigate what's needed - that's if It can be done, assess the amount of work needed, governance to go through, assess the priorities and get back to you with the order of magnitude costs for you to sign off - How soon can you set up the triage with all the relevent SMEs to answer my questions?