Entrepreneurs: the post-money valuation of your last round is a standard bit of info to give to new investors, even prior to the first meeting (if they ask for it prior to the meeting). Many, if not most or even all, investors will ask you for it anyway at the conclusion of the first meeting, and you should offer it up immediately, without hesitation. Investors use it to triage deals. If they like your idea, they may decide whether to pursue it, based in part on how high your last valuation was. It is an advantage to generating interest with new investors that your post-money on your last round was not too high – that’s what they’re really trying to suss out by the question: not spending time on due diligence for a deal where, because of last-round valuation, the expectations of either the entrepreneurs or the investors (or both) are too high. There is no harm in giving it, and to bob and weave in response to the question makes you seem naively evasive -- a bad attribute to convey to an investor.
N.B.: for the reasons set out in my earlier blog post here, this is different (even contrary) advice than I give for disclosing what your valuation expectations are for the financing round that you are currently raising, or, as discussed in another earlier blog post here, what your exit plans are.