Big Congrats Will!
The 1st sale always takes forever, then after that they start coming easier and hopefully faster.
300 clicks is not enough to judge though. I'm guessing maybe the 1st 200 where not as targeted or your copy was not as good as you were learning and building things up. It's possible in 50 clicks you'll make another sale. So I'd hang tight, maybe add something but don't get rid of that one yet unless you find there are leaks or something.