Adwords - how to buy out zero competition KWs?

Hello,

I'm starting to experiment with buying Adwords ads and I'm targeting a set of keywords with zero competition and ~8000 monthly searches. I am targeting global.

One day in, I've only served 20 impressions (with 1 click). I'm doing CPC bidding.

How can I get way more impression share? There's no one else bidding on these keywords..

Thanks