One way to fake a leading indicator is to increase headcount and cash burn rapidly. Those increases create a "hockey stick" graph. Just use that graph when pitching to investors.

You can also time it so that your ad spend doesn't hit until the next financial period, which makes it look like there is actual growth commensurate with the headcount increase and disproportionate (in a good way) to cash burn. After all, what kind of founder would increase headcount unless it was needed :)

Disclaimer: This works best when pitching a round after you have already got some early investors to help with the sales pitch to the next round of investors.