I think your acquisition plan, especially since it's paid, is quite aggressive without a significant investment unless (and perhaps even if) you are solving a prevalent, high-pain-point problem in a way that is easy to understand and difficult to mimic or for which there is no similar or alternate solution.

Most of the advice I would offer has already been stated and, without knowing specifics, it's hard to pinpoint a solution. General advice rarely works for all cases.

I agree that great content marketing is probably part of the mix, although that's rarely a quick path to growth. You may also find inspiration in Growth Hacker Marketing: A Primer on the Future of PR, Marketing, and Advertising by Ryan Holiday a useful quick read on how services like Uber, Box, AirBnB and others quickly entered a new market and achieved uncommon customer acquisition success.