Probably an equity question too. If you demo in March and look for funding, your answer is your valuation. Write $4mil, VC gives you 2mil, they get 50%.
maybe i'm misunderstanding you, but the question is hypothetical and your response isn't shared anywhere outside the app. (i.e. you're not binding yourself to anything by claiming a particularly high or low valuation)
on another note, your company's valuation is determined by what people are willing to pay :)
I look at it as the reserve price of an auction. Ultimately, a startup is worth what people are willing to pay for it, but under a certain price, I'd rather hold onto the startup and try to grow it than sell it.