When you state a % you are being pragmatical, but if you are rasing a convertible note valuation might not be so clear you will then be defining a cap and a discount. Silicon Valley VC's want to understand more what your burn rate is for the next "x" months and what would be your next funding or goal event. So in that sense you might find that your ask will be for the total amount needed to cover full expenses for a team of 5 for 18 months at $10-15K in a city like San Francisco till you reach your next milestone or funding event.

Happy to talk more strategy on a call

Yes. Otherwise you risk setting false expectations for the investor. You can always accept negotiations.

Exceptions include the investor you might want at any valuation to gain benefits over the investment by the party to whom you are addressing.

Are you raising on pure equity? Safes? Convertible Note? The more details you provide to the investor the better. The trouble is the timing, you want to hook an investor on the idea and make them believe that they need to invest.