Rate of Reaction Graph - Gas Produced
I think the first bit of gas produced probably dissolved in the water, so you didn't see it for a little while. 

You can skip your three initial "points" with zero volume, and you're not going to have $\ln(0)$, which is what's hanging you up. Note that you did this in your report, and why!

Do a linear fit with the remaining points. Your y-intercept will be $\ln \mathrm{[A]}_0$ and your slope will be $-k$. It's not a terribly good fit.