Is anyone using the Google AdWords Budget Optimizer?

I read about it, and was considering enabling it on some of my campaigns, but am unable to locate how to do so. The help pages say it's on the edit campaign page near where the daily budget setting is shown, but I see no option as they mention to enable Budget Optimizer. I have checked on multiple campaigns, including those I definitely know have less than 1000 keywords in them.

Can anyone else access this option?